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This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution
and sharing with colleagues.
Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party
websites are prohibited.
In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information
regarding Elsevier’s archiving and manuscript policies areencouraged to visit:
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Review
Sadness as a passion of the soul: A psychopathological consideration of theCartesian concept of melancholy
Francisco López-Munoza,b,∗, Gabriel Rubioc, Juan D. Molinab,d, Cecilio Alamoa
a Neuropsychopharmacology Unit, Department of Pharmacology, Faculty of Medicine, University of Alcalá, Ctra. Madrid- Barcelona, Km. 33,600,Alcalá de Henares 29971, Madrid, Spainb Health Sciences Faculty, Camilo José Cela University, C/Castillo de Alarcón, 49, Villafranca del Castillo 28692, Madrid, Spainc Department of Psychiatry, “Doce de Octubre” University Hospital, Complutense University, Avda. Córdoba, s/n, Madrid 28041, Spaind Acute Inpatient Unit, Doctor R. Lafora Psychiatric Hospital, Ctra. de Colmenar Viejo, Km. 13,800, Madrid 28049, Spain
a r t i c l e i n f o
Article history:Received 8 June 2010Received in revised form 12 January 2011Accepted 31 January 2011Available online 18 February 2011
Keywords:DescartesHistory of psychiatryMelancholyPassionsPineal glandSadnessSoul
a b s t r a c t
The relationship between the “passions” (emotions or feelings) and psychopathology has been a constantthroughout the history of medicine. In this context, melancholy was considered a perversion of the soul(corruption of the passions). One of the most influential authors on this subject was René Descartes, whodiscussed it in his work The Treatise on the Passions of the Soul (1649). Descartes believed that “passions”were sensitive movements that the soul experienced due to its union with the body (res extensa). Accord-ing to this theory, the soul was located in the pineal gland, where it was actively involved in overseeing thefunctions of the “human machine” and kept its dysfunctions under control, by circulating animal spirits.Descartes described sadness as one of “the six primitive passions of the soul”, which leads to melancholyif not remedied. Cartesian theories had a great deal of influence on the way that mental pathologies wereconsidered throughout the entire 17th century (Spinoza, Willis, Pitcairn) and during much of the 18thcentury (Le Cat, Tissot). From the 19th century onwards, emotional symptomatology finally began to beused in diagnostic criteria for mood disorders.
of human nature ever since classical Antiquity. This is to a largeextent due to their close spiritual links with the concept of thehuman soul [5]. Indeed, both Plato (427–347 B.C.) and Aristotle(384–322 B.C.) thought that the passions created distortion anda lack of balance, as they were thought to be the “animal part” ofman. As a result, in Greek culture the belief took root that the pas-sions altered the cognitive processes – mainly the emotions – andwere the cause of madness. For this reason, it was impossible forthe diseases of the soul, including melancholy, regardless of their
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cause, to be anything but a perversion of the amina [23], a corrup-tion of the passions, the “animal part” of the human being – theresult of a process of disorder and chaos. This idea, as defined byvarious authors, was common currency until almost the end of the19th century [5].
One of the history’s most influential authors in this field wasthe great philosopher René Descartes (1596–1650), who providedan entire neuropsychophysiological doctrine on this subject. As iswell known, Descartes postulated that the human soul must havea specific anatomical location. He believed that from this posi-tion, the soul supervised the communication between the humanmachine and its surroundings, and acted as an internal influencewhich exerted control over the precise functioning of the humanbody, including the passions. In the French philosopher’s opinion,the divine spirit exercises its functions in the pineal gland [37]. Hebelieved that the pineal gland was actively involved in the dysfunc-tions of the “human machine,” and because it was where the soulwas located, it played a key role in psychiatric disorders. Indeed,Descartes believed sadness to be a “passion of the soul,” which ledto melancholy if it was not remedied.
However, it was not until the 19th century, as a result of roman-tic and positivist medical trends, that the emotions began to be usedin the definition and construction of mental illnesses on a scientificbasis [5]. From that point on, emotional symptomatology becamepart of the diagnostic criteria for numerous pathologies in the psy-chiatric field, and especially those of an emotional nature. Likewise,and especially from a semantic perspective, the idea of melancholybegan to be supplanted by the idea of a mood disorder, or moresimply, a depressive disorder. This entity is now considered to bethe most common psychiatric disorder, and according to variousepidemiological estimates, may affect up to 25% of the population[40].
In this study, we will consider the Cartesian theories on thepassions and their corruption as the root of melancholic mood dis-orders. These theories are based on a physiological explanation ofthe functioning of the human body which is especially thought-provoking in modern times, despite its errors, historical limitationsand nuances.
2. Historical background
Mood disorders, described in classical terms as “melancholy,”were possibly the clinical entities that were the first of all themental illnesses to be subjected to analysis. However, the under-standing of human spirituality has undergone profound changesthroughout the history of western culture. The various theoriesof the philosophers and physicians of classical Antiquity and theimposition of Christian doctrine during the High Middle Ages ledto the creation of a “seedbed,” which made the emergence ofthe Cartesian psychophysiological and psychopathological theoriespossible. These factors will be analyzed in more depth below.
From the neurophysiological perspective, the School of Alexan-dria in Ptolemaic Egypt, the most distinguished representatives ofwhich were Herophilus of Chalcedon (325–280 B.C.) and Erasistra-tus of Keos (310–250 B.C.), established a way of understanding howthe nervous system worked that could be described as pneumatic-ventricular. These authors believed that after being transportedfrom the lungs to the heart, air (cosmic pneuma) was turned intopneuma zootikon (spiritus vitalis, in Latin) in the heart, and was sub-sequently sent by means of the blood to the brain, where it becamepneuma psychikon (spiritus animalis, in Latin) in the cerebral ven-tricles. However, it was Claudius Galenus, or Galen of Pergamon(131–200), who adapted this pneumatic theory, and created a phys-iological doctrine that would endure until the age of Descartes [21].Like Plato, Galen divided the soul into three parts: appetitive, spir-
ited and rational (located in the liver, heart and brain respectively)and talked about the three types of spirits or pneumatas (physi-cal or natural, vital and psychic) that made up the human faculties(dynamis). He believed that these spirits were very subtle physi-cal substances, which circulated in the various liquids of the body.The blood pumped in the heart was therefore directed to the retemirabile of the brain, and created psychic pneuma or spiritus ani-malis in the lateral ventricles. This pneuma was then transferred tothe spinal cord and the nerves (which were thought to be hollow)as an inductor of the dynamis psykhiké, which caused a muscularaction [28]. As Spillane [55] points out, Galen’s “hydraulic” theoryof the spirits was the most enduring idea in the history of science.
In psychopathological terms, the doctrinal corpus of the CorpusHippocraticum (5th and 4th centuries B.C.) maintained that the var-ious parts of the organism, including the soul, were formed by themixture of the four humors (blood, phlegm, yellow bile and blackbile) in varying proportions (Fig. 1). Health was the result of a bal-anced mixture, while diseases, including those of the soul, were todue to an imbalance in the mixture of the humors, and the con-sequent predominance or lack of one or more humors and theirrespective qualities. In specific terms, humoralist thinkers believedthat melancholy was caused by an excess of black bile (melas chole)or atrabilis (“dark bile”, in Latin). Meanwhile, following Alexandrianpneumatic doctrine, Aretaeus of Cappadocia (1st and 2nd centuriesA.D.) considered the illness to be a dyscrasia in the correct mixtureof the four elemental qualities (heat, cold, dryness and moisture).This led to an alteration in the dynamic of the pneuma or spiritus, arefined product of inhaled air, through the ducts of the body [23].These theories were the foundations on which Descartes built hispsychophysiological doctrine.
Aristotelian philosophical ideas were also the cornerstone ofapproved medieval philosophy. With the rise of Christianity, dur-ing first the Patristic and subsequently the Scholastic period, thetheological properties of the soul became more important, and itsfunctional properties were of less interest. In an accomplished exer-cise in syncretism, Saint Thomas Aquinas (1225–1274) [50] made adistinction between a number of biological and relational functions(such as sensory perceptions) common to both men and animals,and the cognitive powers (or passions) that only human beings pos-sessed, which he said were manifestations of the power of the soulover the body. This perspective was changed forever by Descartes,who defined the passions in Article XXVII of The Passions of the Soulas “apprehensions, resentments or emotions of the soul” [1,15].
However, physicians advocating reformed ideas based on theGalenic school, such as Arnau de Vilanova (1235–1313), maintainedthat mental disorders were not the result of changes in the soul, butinstead its bodily instrument, i.e. the brain. Indeed, the intangibleand divine nature of the soul made it difficult to explain why mentalpathologies were a consequence of its involvement. These disorderswere therefore believed to be essentially organic cerebral disorders,despite their hypothetically psychical origin, and were caused byimbalances in the emotions or passions. In his Breviarium PracticaeMedicinae (1483), Arnau de Vilanova specifically attributes the ori-gin of melancholy to an internal dysfunction of the animal spirits,which can lead to fear (timor), sadness (tristitia) and mutism [59].
Medieval ideas on the nature of the human soul continued topredominate during the Renaissance, as did theories on mental ill-ness based on Galenism (as well as a new strand resulting fromChristianity, which was based on moral factors, such as divine pun-ishment and the superstitious belief in the intervention of evil).Among the leading advocates of the classical Galenic theory of thehumors and their involvement in the origin of mental disorderswas Juan Huarte de San Juan (1529–1588). In his only work, Exa-men de ingenios para las ciencias (The Examination of Mens Wits)(1575), Huarte de San Juan says that the proportion in which thehumors are combined determines the various temperaments, i.e.
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Yellow bile Summer
Liver
Heat Dryness
FIRE
Heat Dryness
EARTHWIND
Blood Black bile
Heart EARTHWIND
Spring Autumm
Heart Spleen
Moisture Cold
WATER
Phlegm Winter
Brain
Fig. 1. Diagram showing the classical Galenic theory of the four elements, and the items associated with each one; four qualities, four humors, four organs and four seasons.Adapted from Finger [19].
the predisposition towards the impressions caused by either envi-ronmental factors, or by endogenous factors (memories, ideas, etc.)[41,47]. According to this theory, the predominance of a partic-ular humor led to differences in “wit,” with madness considered aspecial type of “wit” according to this hypothesis. The various men-tal disorders, such as mania, melancholy or frenzy were thereforethe result of a change in the temperament of the patient’s brain.This temperament was reversed when the patient was treated andcured.
The role of animal spirits in human physiology, as tools for com-munication between the upper strata of the being and corporeality,which was even defended by Andreas Vesalio (1514–1564) in hismagnum opus De humani corporis fábrica (Book VII, 1543) [51], andthe role of the humors in the origin of melancholy, were thereforemajor topics of scientific debate in the age of Descartes.
3. The Cartesian psychophysiological perspective
René Descartes (Fig. 2) was one of the most important menof science of the 17th century. Like the great geniuses of theRenaissance, Descartes worked in the fields of philosophy, math-ematics, physiology, physics, astronomy and even music, and hisDiscours de la méthode (1637) was the key scientific manual ofhis time. Descartes was not only the founder of contemporaryphilosophy [26], but was also the father of analytical geome-try (Cartesian algebra). In addition, he formulated laws for therefraction of light (the “Laws of Descartes”) and was a greatscholar of man’s vital signs and physiological activities (Diop-trique, 1637; Descriptio Corporis Humani, 1648; Les Passions del’Âme, 1649; De Homine, 1662 and Traité de l’Homme, 1664;La Formation du Foetus, 1664).
3.1. Cartesian dualism vis-à-vis the soul and the body
The principles of Cartesian philosophy are based on decipheringthe essence of the cosmos, which has a purely mechanical naturefrom this perspective. Descartes sees the universe (res extensa)as a material and mechanical system which is governed by theinflexible laws of mathematics [15]. However, Descartes uses Greekphilosophical analysis to leave the way open for a duality of thehuman body and soul [8,58]. This would be very important in hisetiopathogenic interpretation of mental disorders, and depression
in particular, as discussed below. In his Méditations Métaphysiques(1641), Descartes says:
“I have a vivid and clear idea of myself as something thatthinks and isn’t extended, and one of body as something thatis extended and does not think. So it is certain that I am reallydistinct from my body and can exist without it” (6th Meditation)[14, p. 27].
Descartes thus removes the soul and intelligence from hisconcept of the cosmos. The soul (res cogitans), is therefore outsidethe external world, which includes the human body (res extensa)and animals. On this point, the French philosopher differs from theclassical Greek theories [27], and adopts the dogmas of some ofthe great Fathers and Doctors of the Church, such as Augustine ofHippo (Saint Augustine) (354–430) [25], who believed that humanbeings consisted of body and spirit, although the body was not
Fig. 2. René Descartes, from an engraving by William Holl, based on an originalportrait by Frans Hals (1648) in the Musée du Louvre (Paris).
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Fig. 3. Covers of the first editions of The Treatise of Man and The Passions of the Soul: (A) The Henry Le Gras edition of Les Passions de l’Ame (París, 1649). (B) The Florent Schuyledition of L’Homme published in Latin, entitled De Homine (Leiden, 1662).
the prison of the soul: the soul was located in each part of thebody (De Trinitate, 399–419). Descartes also acknowledged theexistence of an intangible mind or soul (res cogitans), which wascompletely unencumbered by the laws of mechanics, and whichhad inner perceptions that he called passions. As well as this res,and subordinate to it, there was a material entity or animal body(res extensa); both res existed in perfect harmony to constitute thehuman being [32]. In his work The Treatise of Man (1664) Descartessays: “I assume the body to be but a statue, an earthen machine,formed intentionally by God to be as much as possible like us [Art.2]. When God will later join a rational soul to this machine, Hewill place its chief seat in the brain” (Art. 28) [1,16]. It is thereforeprecisely the acknowledgement of the principle of spirit-matterdualism which opens up a small chink in Descartes’ determineddefense of his mechanistic doctrine.
This dualist stance by Descartes has been openly criticized bysome contemporary authors, including the neurologist AntonioDamasio (1944–). In his work Descartes’ Error: Emotion, Reason, andthe Human Brain (1994), Damasio says that the separation of mentalactivity from the structure of the brain and its inner workings is aserious error [12]. This is because the brain and the rest of the organ-ism form an inseparable entity consisting of numerous neuronaland biochemical channels that relate the subject to its surround-ings, and mental activity is a result of this interaction. However, inhis final work published during his lifetime (The Passions of the Soul,1649), Descartes makes it clear that the relationship between thesoul and the body is something more than the sum of its two parts.For this reason, some authors [31] mention “triadism” when dis-cussing the Cartesian theories advocated in this work, as it suggestsa “third distinction” or “quality,” which is the interaction betweenthe two substances that make up human beings, as an experience ofunity. In fact, regardless of whether the soul’s functions has a spe-cific influence on particular anatomical structures, in Article XXXof The Passions of the Soul, Descartes states that “the soul is reallyjoined to all the body, but it cannot properly be said to be in any ofthe parts thereof, excluding the rest, because it is one, and in somesort indivisible” [1,15].
3.2. The functionalism of the human body according to thetheories of Descartes
First, it must be emphasized that Descartes used two types oftechnical sources. On the one hand, in his philosophical work headopted most of the theories that had been common currency sinceclassical Antiquity, which were essentially the ideas of the Alexan-drian pneumatic school as regards the so-called “animal spirits”(“copula animae cum corpore”), which were subsequently “Chris-tianized” by Saint Augustine: “Et aer, qui nervis infusus est, paretvoluntati, ut membra moveat, non autem ipse voluntas est” (De Genesiad Litteram, 401–415). These spirits are the “biochemical” founda-tions for all Cartesian neuropsychophysiological doctrine, whichis the same as Augustinian neurophysiology in many aspects [52].However, the physiological sources upon which he based his doc-trine were entirely contemporary. As Brett [7] correctly points out,in the field of physiology, Descartes had the advantage of comingafter Vesalius, and the luck to find out about Harvey’s discovery.
Much of Cartesian physiological doctrine is contained in theTraité de l’Homme (Fig. 3), which was possibly the most influentialwork on the conception of human psychophysiology in the entire17th century, and is considered the first European physiology text-book [48]. The Treatise of Man was originally supposed to be chapterXVIII of a more extensive work, The Treaty of Light or The World (DuMonde). However, Descartes never published this magnum opus,as he stopped working on it when he heard that the Inquisitionhad condemned Galileo Galilei (1564–1642) (Dialogo sopra i duemassimi sistemi del mondo, tolemaico e copernicano, 1632) in 1633.The extent to which the philosopher’s state of mind was affectedby the guilty verdict passed on Galileo can be seen in the letterhe wrote to his friend, Father Marin Mersenne (1588–1648), on28 November 1633, in which he said that this condemnation forthe “Copernican heresy” “. . . has shocked me so much that I havealmost to burn all my papers, or at least not to let anyone see them.However, just as I would not want for anything in the world toproduce an essay containing the least word that would be disap-proved by the Church, so I would rather suppress it than publish
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Fig. 4. Engraving by Louis de la Forge to illustrate Article 61 of The Treatise of Man(1667), entitled “On the structure of the brain of this machine.” The pineal gland ismarked by the letter H.
it maimed.” [1,46, p. 93]. Some authors have even suggested thatthe trial of Galileo, which was held in September 1633, influencedDescartes’ thought to such an extent that it made him “tone down”the neurophysiological theories he set out in The Treatise of Man,in which the body-mind materialist dualism is apparent. When hewrote The Treatise on the Passions of the Soul, his neurophysiologicaltheories gave the rational soul the role of controlling the functionsof the “human machine,” which was more in line with the officialAugustinian doctrine of the Church [42].
As a counterpoint to the architectonic Renaissance anatomy ofVesalius, Descartes proposed a completely mechanical concept ofthe activity of the human body, the functioning of which could beexplained without the need for considering external possibilities.Indeed, the French philosopher is considered to be the inventor ofthe “man-machine,” a concept which considers the human beingto be an organism consisting of several parts, of which it is thesum. Furthermore, based on these theories, the movement of theparts comprising the living being must obey the same laws as thosethat govern the rest of the universe [8]. In The Treatise of Man,Descartes mentions the major breakthroughs in what were knownas automata during the Renaissance (clocks, religious and courtlyfigures, mills, etc.), and formulates a complex mechanistic phys-iological doctrine. However, in Descartes’ opinion there is a cleardifference between the “moving machines that human industry canmake” and human beings, as this machine, “having been made bythe hands of God, it is incomparably better organised – and capableof movements that are much more wonderful – than any that canbe devised by man” (Discourse on the Method, Part 5) [1,13, p. 22]
For Descartes, the nervous system consisted of the brain andthe nerves. He believed that the brain (Fig. 4) was formed by threedifferent parts; the outer layer (surrounded by the pia mater), theinner layer (the ventricle walls) and the substance of the brain,located between the two layers. In his anatomical view, the innerlayer is the most important part of the brain and is completely
Fig. 5. Diagram by Louis de la Forge for The Treatise of Man (1667), showing theCartesian anatomical structure of the nerves. Based on Art. 18: “Explanation of theproduction of nerves”.
covered with pores, which are the spaces between the nervous fil-aments which make up a type of grid or network. These filamentsgo straight to the outer layer of the brain (the shorter ones), or formpart of the nerves in the stricter sense which are located through-out the body (the longer ones). Instead of the classical concept,which associated nerves with hollow channels and was still preva-lent during the 17th century, Descartes advocated a system thatalso included the existence within them of a delicate network offilaments or fibers that mingled with the filaments comprising thebrain, and enabled the existence of spaces between them for theappropriate flow of animal spirits (Fig. 5):
“Observe, for example nerve A, whose external membrane is likea large tube containing several other small tubes, b, c, k, l, andso on, composed of a thinner, internal membrane; and observethat these two skins are continuous with the two, K and L, whichenvelop the brain M, N, O.
Observe also that in each of the little tubes there is a sort ofmarrow composed of several very fine fibrils which come fromthe actual substance of the brain and whose [two] extremitiesend [one] at the internal surface of the cavities of the brain and[the other] at the membranes and flesh on which the tubulecontaining them terminates” (Art. 19) [1,16].
The nerves ended in the muscular mass and at this level, hadvalves that enabled the animal spirits to enter the muscle. On theirjourney around the body, the nerves also had a distal valvular mech-anism, similar to that proposed by William Harvey (1578–1657) inhis description of blood circulation, to maintain and control thespiritual flow [53]. Although the philosopher had absolutely noknowledge of the motor tract and only describes a sensory nervoustract, it is easy to deduce a logical explanation for this problembased on his theory: the cords or small filaments making up thenerves (the continent) are therefore responsible for sensitivity, andanimal spirits (the content) account for motility.
As a result, according to Descartes’ psychophysiological theo-ries, the tranquil harmony between the desire of the mind and the
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Fig. 6. Anatomical location of the pineal gland, according to the theories of Descartes and the interpretation of the illustrator, Florent Schuyl (Figure XXXIV of De Homine,1662).
movement of the body required perfect communication, for whichthe Galenic spiritus animalis were responsible. However, the natureof these spirits is not made particularly clear in Descartes’ works.Like Tertullian of Carthage (155–230), Descartes thought that ani-mal spirits were not a liquid substance, but instead subtle fluidsinside the cerebral ventricles and the nerves – as rapidly mov-ing particles. In short, he saw them as a type of “quintessence”caused by a loss of blood density. It therefore appears thatDescartes was unaware of the discovery of cerebrospinalfluid by Niccolò Massa (1485–1559), in 1536 (Anatomiae LibriIntroductorius).
3.3. The pineal gland as the Cartesian anatomical centre ofhuman psychophysiology
In the Cartesian theories, in order for this harmonious relation-ship between the mind and body to exist, it is necessary for the rescogitans or human soul to have a corporal and physical seat, fromwhere it would be possible for it to undertake this mysterious com-munication. Descartes therefore established the seat of the soul in“the innermost of the parts of the brain”, i.e. the pineal gland (theclassical epiphysis cerebri) [37].
However, it should be pointed out that the anatomical locationof the pineal gland in The Treatise of Man is erroneous. Descartessituated this organ in the rostral part of the sulcus lateralis cere-bri, which connected the third cerebral ventricle with the fourthventricle [8], “a well protected place, which is almost immuneto diseases” [19]. Within this anatomical region, the pineal glandphysically hangs from arterioles and is not attached to the sub-stance of the brain (Fig. 6). Although the illustrations in The Treatiseof Man include an obvious error, by showing the pineal gland asbeing inside the ventricles, they are possibly not the result of a gapin the anatomical knowledge of Descartes himself. Claude Clerse-lier (1614–1684), the philosopher’s brother-in-law and friend, whopublished of the French version of the treatise, commissioned Louisde la Forge (1632–1666), a doctor in medicine in La Flèche, andGérard van Gutschoven (1615–1668), a professor of anatomy atLouvain and an advocate of the mechanistic Cartesian theories,to produce these illustrations fourteen years after the author’sdeath. As a result, the drawings were simply the interpretations ofthe illustrators, supervised by Clerselier, of Descartes’ posthumouswork (in fact, by drawing the pineal gland much larger than its nat-ural size, the illustrators highlighted the importance that Descartesconferred on this organ) (Fig. 4) [6,54]. Furthermore, according toCarter [8], the anatomical dissection techniques of the time werenot sophisticated enough to be able to ascertain the precise location
of the pineal gland, and as a result many authors suggested that itwas located inside the substance of the brain.
In any case, Descartes believed that the inner structure of thepineal gland, like that of the rest of the brain, consisted of fila-ments separated by pores through which blood from the plexuschoroideus and the epiphysary arterioles flowed [53]. In order tocarry out its function, the pineal gland exuded fine particles sus-pended in the blood and created in the left ventricle of the heart,by the heat of the myocardium (“a very subtle wind, or rather aflame which is very pure and very vivid,” in Descartes’ own words)(Art. 14) [1,16] which transformed them into esprits animaux. Thelarger particles, meanwhile, as they were not filtered by the pinealgland, went to the surface of the brain cortex for nutritional pur-poses [6]. These spirits had two fundamental properties: they arevery small particles and move very quickly “as the parts of a flameissuing from a torch” (Art. X) [1,15].
In Cartesian physiology, figures from the outside world firstaffected the surface of the ventricles and then, due to the “animalspirits” within them, they marked the surface of the gland like a“seal in wax” [58]. The pineal gland was in turn responsible for themovements of the distal muscles, which also took place by meansof animal spirits [38]. Active movements of the gland sent themto the cerebral ventricle system (the Cartesian cerebral cavities)and from there to the outer regions of the body, passing throughthe vast amount of pores that in theory were within the walls ofthe ventricles. According to this physiological theory, the ventric-ular pores were able to open or close depending on the type anddegree of sensory stimulation, and could thereby limit the flow ofanimal spirits from the pineal gland to the muscles along the nervetubes. Once these spirits reached the muscle, they made it changeits shape, producing movement of the muscle. The entire processis summarized in The Treatise of Man with the help of a drawing(Fig. 7):
“You can see in the diagram that the spirits that leave the gland,having dilated the part of the brain marked A and having partlyopened all its pores, flow thence to B, then to C, and finally intoD, whence they spill out into all the nerves. And by this meansthey keep all the filaments that compose the nerves and thebrain so tense that even those actions that have barely forceenough to move them are easily communicated from one oftheir extremities to the other, nor do the roundabout routesthey follow prevent this” (Art. 65) [1,16].
When providing this mechanical explanation for the physio-logical phenomenon, Descartes had the advantage of an assumedmobility of the pineal gland (Fig. 7) [20], as: “. . . it is composed
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48 F. López-Munoz et al. / Brain Research Bulletin 85 (2011) 42–53
Fig. 7. Engraving by Gerard van Gutschoven, based on Art. 64 of The Treatise of Man(1667) (“How ideas of objects are formed in the place destined for imagination andfor common sense”).
of matter which is very soft and that it is not completely joinedand united to the substance of the brain but only attached to cer-tain little arteries, whose membranes are rather lax and pliant; itis sustained as if in balance by the force of the blood which theheat of the heart pushes thither” (Art. 72) [1,16]. This ability of theepiphysis to move in order to regulate the flow of animal spirits issimilar to the role of a valve in mechanical terms, and could alsobe caused by the force of the animal spirits which pass through itand by the action of the objects that reach the senses. However,Descartes was not the pioneer of this valvular concept, accord-ing to some authors [49], as it had been proposed by Jean Fernel(1497–1558), a modern advocate of the Galenic medical system(Universa medicina, 1554) a century earlier. However, Lokhorst andKaitaro [36] maintain that the anatomical structure that Fernel dis-cusses is not the pineal gland, but in fact the cerebellar vermis (aspostulated by Galen and Costa ben Luca or Constabulus, 864–923),which would mean that Descartes’ theory is in this case completelyoriginal.
However, as well as physical factors, the gland could also “bemoved” directly by the force of the soul, an idea which is directlyrelated to Descartes’ psychological theories. Descartes discussesthis role in detail in his work The Passions of the Soul, in which hestates that it:
“. . . hangs so between the cavities which contain these spir-its, that it may be moved by them as many several fashions asthere are sensible diversities in objects. But withal, that it maybe moved several ways by the soul too, which is of such a nature,that it receives as many various impressions (that is, has as manyseveral apprehensions) as there come several motions into thiskernel. As also on the other side, the machine of the body is socomposed that this kernel being only divers ways moved by thesoul, or by any other cause whatsoever, it drives the spirits thatenviron it towards the pores of the brains, which convey themby the nerves into the muscles” (Art. XXXIV) [1,15].
As a result, “all the action of the soul consists in this, that itmerely by willing anything can make the little kernel, whereunto itis strictly joined, move in the manner requisite to produce the effectrelating to this will” (Art. XLI) [1,15], so that it could cause musclemovements by positioning itself in such a way that the spirits slidethrough different pores in the ventricular walls. In short, Descartesbelieved that every change in the position of the pineal gland leadsto a different perception of the soul, and the soul in turn could alsomove the gland merely as a result of perception [8].
However, “. . . the little kernel in the middle of the brain, beingdriven on one side by the soul, and on the other by the animalspirits (which are only bodies, as I laid down before) it happensoftentimes that these two impulsions are contrary and that the
Fig. 8. Drawing included in Art. 76 of The Treatise of Man (1667), showing “How anidea can be formed from several movements”.
strongest hinders the operation of the other” (Art. XLVII) [1,15].For Descartes, there were therefore two types of movements bythe pineal gland that could have been caused by spirits; those thatpresent the objects captured by the senses to the soul (Fig. 8) andthose that cause the passions (Art. XLVII) [1,15]. The former haveno power over the will, while the latter do have this power. A soulwill therefore be stronger when its will can easily prevail over thepassions and can neutralize the movements of the body that accom-pany them. However, “. . . even those who have the weakest souls,may acquire a most absolute empire over all their passions, if artand industry be used to manage and govern them” (Art. L) [1,15].
However, why did Descartes believe that the pineal gland wasthe control centre of the body, and the seat of the sensorium com-mune (the point of convergence of all the sensations in the brain)and the seat of the soul (siège de l’àme)? His choice was possiblybased on anatomical reasons [18], although mathematical reasonscannot be ruled out, as Descartes selected an organ located in theexact geometric centre of the brain. Descartes was possibly awareof the work and opinions of the famous professor of Anatomy atUtrecht University, Ysbrand van Diemerbroeck (1609–1674), whowas a contemporary of the French philosopher. Van Diemerbroeckhad already postulated the pineal gland as the possible locationof the sensorium commune, the place where all types of sensorystimuli converge. In any event, Descartes believed that there weretwo of each of the sensory and cephalic organs, except for thissingle small gland (“where the seat of common sense and imag-ination is,” the store of past experiences and the organ responsiblefor “appetites and passions”) located in the geometrical centre ofthe brain (primus inter pares) and suspended over the channels thatcontained the animal spirits (Figs. 4, 6 and 8) [9]. This central loca-tion enabled it to receive any stimulus from the peripheral organs,while its unitary nature means that the process of assimilating per-ceptions and sensations from double organs is possible (Fig. 8).Taking these physiological ideas as their cornerstone, the Carte-
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sian theories reached one of the greatest landmarks in mechanisticphilosophy, which takes us back to the preface of The Treatise ofMan, in which he compares these men-machines to the fountainsthat adorn royal gardens [38]. Descartes was also one of the firstscientists to consider the problem of the location of the cerebralfunctions, albeit erroneously in the light of current knowledge [37].In this area, his theories presaged the major work done by ThomasWillis (1622–1675).
4. The passion of the soul in Cartesian philosophy
One of the major controversies in Cartesian philosophical doc-trine is the influences that act on thought (res cogitans) andextension (the human body-machine) [2,24,57]. In the philoso-pher’s opinion, the possible relationship between both entities istwofold, as it is possible that the soul moves the body, and thatthe body is in turn able to influence the soul. Descartes uses theterm “passion” to refer to this interaction, and defines these as thesensitive movements experienced by the soul as a consequenceof its union with the body. It must be borne in mind that themeaning of the word “passion” in Cartesian doctrine would be theequivalent of the concept of “emotion” in modern psychology [56].Descartes focused on this issue in his final work published duringhis lifetime, The Treatise on the Passions of the Soul (Fig. 3). Someauthors have suggested, from psychophysiological point of view,this may be a type of continuation of The Treatise of Man [35],although its starting point is the correspondence that Descartesmaintained with Princess Elizabeth of Bohemia (Elisabeth von derPfalz) (1617–1680), the abbess of Herford, and his meditationson happiness. Indeed, in a letter dated 21 May 1643, Elizabeth ofBohemia asked Descartes about the internal interactions of the souland matter. The philosopher replied:
“In view of my published writings, the question that can mostrightly be asked is the very one that you put to me. All the knowl-edge we can have of the human soul depend on two facts aboutit: the fact that it thinks, and the fact that being united to thebody it can act and be acted on along with it. I have said almostnothing about, focussing entirely on making better understood.That is because my principal aim was to show that the soul isdistinct from the body” [1,4, p. 2].
This led to Descartes’ final work, which was originally entitledLes Passions de l’âme, and was published simultaneously in Hollandin 1649 by Louis Elzevier (1540–1617), and in France by Henry LeGras (1590–1662), just a year before the philosopher’s death. Thegeneral theme of this work is a description of how the soul is joinedto the body. However, when considering this problem, Descartes,as he makes clear in the prologue, does not do so from a moral-istic or philosophical point of view, but instead from the physicalpoint of view. He therefore considered it in specifically scientificand physiological terms [15]. For Descartes, thoughts were amongthe exclusive properties of the soul. These may in turn be of twotypes; actions of the soul, i.e. volitions that come directly from thesoul, and passions of the soul. The latter are our perceptions ofobjects that stimulate the nerves, or are due to other less commoncauses, such as fantasies of the imagination that stir the soul, thetemperament or the intellectual emotions.
Descartes defined the passions of the soul, of which he lists49, as “. . . apprehension, resentments, or emotions of the soul,attributed particularly to it, and caused, fomented, and fortifiedby some motion of the spirits” (Art. XXVII) [1,15]. The Frenchthinker felt that the best definition of the three alternatives wasthat of an emotion of the soul, i.e. a movement or change of thesoul due to the thoughts reaching it. However, a distinction mustbe made between these sensations and those that refer to phys-
ical objects (odors, colors, sounds), and those that involve thebody itself (thirst, hunger, pain), as these emotions, called pas-sions, are created by the soul itself. The function of the passionsof the soul is also perfectly explained by Descartes when he saysthat “. . . use of all the passions consists only in this, that theydispose the soul to will the things which nature dictates are prof-itable to us, and to persist in this will. . . to dispose the body tothe motions that further the execution of those things” (Art. LII)[1,15].
4.1. Sadness as a passion of the soul
In Descartes’ opinion, there were only six primitive or primarypassions, which are indivisible, as referred to in Art. LXIX in hiswork The Passions of the Soul: “. . . it may easily be noted thatthere are but six such, to wit: admiration, love, hatred, desire, joyand sadness, and all the others are compounded of some of thesesix, or are sorts of them” [1,15]. Sadness is therefore one of thesix pure passions of the soul. He also established the existence oftwo “sorts” of sadness (Art. LXII), pity and envy, both of which aredescribed as a consequence of our impressions of other people orgroups.
Sadness is defined as “an unpleasant languishing, wherein con-sists the discommodity the soul receives from evil, or defect, whichthe impressions of the brain represent unto her, as belonging to her.And there is also an intellectual sadness, which is not the passion,but which wants but little of being accompanied by it” (Art. XCII)[1,15]. However, Descartes says that “it oft falls out, that a man issad or joyful, and yet he cannot distinctly observe the good or evilwhich are the cause of it” (Art. XCIII) [1,15]. This is for two reasons:because they are associated with the perceptions of the body (asadness associated with a bodily dysfunction or the perception ofpain, for example) rather than the soul, or because the soul doesnot recognize them as good and evil, but thinks of them in anotherway, but they act in a similar way on the brain.
For Descartes, except for admiration, the other primitive pas-sions, including sadness, not only originated in the brain, but also“. . . in the heart, spleen, liver, and all other parts of the body, in asmuch as they serve to the production of the blood, and afterwardsof the spirits” (Art. XCVI) [1,15], as the force of the blood in the veinsvaries under different circumstances, as does the extent to whichthe entry cavities to the heart are opened. At the base of the heartare some small nerves which narrow or widen the entries to thecardiac cavities. As a result, the blood can spread to a greater orlesser extent in the cardiac cavities, in order to produce spirits ofvarious moods and different qualities. Hence:
“. . . in sadness, the pulse is weak and slow, and a man feelsstrings about his heart, which bind it close, and icicles that freezeit and communicate their cold to the rest of the body. Yet despitethat he has sometimes a good appetite, and feels his stomach notfailing of its duty, provided there be no hatred mingled with thesadness” (Art. C) [1,15].
According to Descartes, when a joyful thought affects the brain,animal spirits are conveyed intensively towards the nerves locatedaround the chambers of the heart. These orifices are enlarged, mak-ing the blood circulate more quickly, producing “spirits, whoseparts being very equal and subtle, are fit to form and fortify theimpressions of the brain, which deal lively and quiet thoughts tothe soul” (Art. CIV) [1,15] (this explanation suggests a type of posi-tive feedback). However, in sadness the opposite is true; the cardiaccavities are narrowed, the blood is “no whit agitated” and verylittle of it reaches the heart. Furthermore, “the passages throughwhich the juice of meats glides from the stomach and entrails tothe liver are open, wherefore the appetite diminishes not” (Art.CV) [1,15]. Descartes suggested a hypothesis of a psychoanalytical
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nature, when he states that “the first sadness” is associated withlack of food. Indeed, the lack of food supplying the heart causesits entry orifices to contract, as a result of receiving little blood.As a compensatory measure, the spirits contribute to a reductionin blood from the spleen, as this organ “is the last reserve whichserves to supply the heart, when there comes none to it from anywhere else” (Art. CX) [1,15].
As can be deduced from all the psychological theories men-tioned above, for Descartes the heart was the “source of the passionsseeing it prepares the blood and spirits to produce them” (Art. CXIV)[1,15].
4.2. The symptomatological manifestations of sadness as apassion of the soul
In the Treatise on the Passions of the Soul, Descartes also gavethorough consideration to the physical manifestations of thesepassions, which he calls “corporeal movements.” According toDescartes, sadness is usually accompanied by paleness, trembling,listlessness, tears and sighs. Paleness is an intrinsic characteristicof sadness and is physiologically justified:
“On the contrary, sadness, by contracting the orifices of theheart, makes the blood flow more slowly into the veins, and thatbecoming colder and thicker has not need of so much room; sothat retreating into the largest, which are nearest the heart, itdeserts the remotest. The most apparent whereof being those ofthe face, that makes it look pale and wan, especially when thesadness is great . . ..” (Art. CXVI) [1,15].
The cause of the trembling that accompanies sadness is that theblood of individuals experiencing this passion is too thick, so thatnot enough spirits are produced to reach the nerves from the brain.Meanwhile, languishing, which “is a disposition to ease one’s self,and be without motion, which is felt in all the members” (Art. CXIX)[1,15], was caused, like trembling, by too few spirits reaching cer-tain muscles. Although there is no decline in their numbers, thepineal gland sends them to different muscles. The “languishing”that accompanies sadness was in Descartes’ opinion mainly dueto the presence of “desire of a thing, to the acquisition whereof aman cannot contribute anything for the present” (Art. CXXI) [1,15].Astonishment or swooning takes place when the life-giving heatof the heart decreases. According to this hypothesis, although thissymptom is usually thought of as common in people affected withsadness, the French philosopher thought that it happened veryrarely. In theory, sadness could close the chambers of the heart, sothat it could extinguish its fire. However, under no circumstancescould there be so little blood inside it that its heat was completelystifled, even when the entry cavities were almost entirely closed.
According to Descartes, tears usually accompany moderate sad-ness, especially when it is followed by another passion, such as loveor happiness. Tears are caused by the vapors that come from theeyes, due to the large size of the optic nerves. Sadness per se is due toa cooling of the blood, which contracts the pores of the eyes, whichin turn leads to a decrease in the amount of vapors that have tocome out through these pores. However, in order for the vapors tobecome tears, the amount of them must increase very quickly. Thisis caused by an increase in the volume of blood sent to the heart bythe passion of love. According to Descartes this is why “they who aresad do not continually shed tears, but only by intervals when theymake any new reflection on the objects they affect” (Art. CXXXI)[1,15]. This sudden abundance of blood makes the lungs also sud-denly swell, thereby forcing out the air they contained. When itleaves the throat, this causes the groans that accompany tears.
Finally, sighs are also usually associated with sadness. Thephysiological justification for this symptom is relatively complex.Descartes himself explains it thus in Art. CXXXV:
“For whereas a man is excited to weep when the lungs are fullof blood, he is incited to sigh when they are almost empty andwhen some imagination of hope, or joy opens the orifice of thevenous artery which sadness had contracted; because then thesmall remainder of blood in the lungs, falling all together intothe left side of the heart through this venous artery, and drivenon by a desire to attain this joy, which at the same time agitatesall the muscles of the diaphragm and breast, the air is suddenlyblown through the mouth into the lungs to fill up the vacantplace of the blood. And this is called sighing” [1,15].
The French philosopher includes a wide range of “particular pas-sions” as subgenres of the “primitive passions.” He mentions severalparticular passions of sadness, including fear, desperation, indeci-sion, remorse, envy, compassion, regret, shame and distaste. Withregard to the latter, which is also known as disgust or revulsion,Descartes says that:
“. . . it is a sort of sadness, proceeding from the same causewhereof joy came before. For we are so made up that themost part of the things we enjoy are only good to us for aseason, and afterwards become incommodious” (Art. CCVIII)[1,15].
The passions “all relate to the body, and are not given to thesoul, but as joined to it. So that their natural use is to incite the soulto consent and contribute to the actions, which may be useful toconserve the body, or make it in some kind more perfect.” In thisrespect, Descartes believes that all the passions are necessary (theyare beneficial by nature, he says, in this case agreeing with the Aris-totelian theories) and even that “sadness is in some sort superiorto, and more necessary than joy. . ., because it is of more momentto repel things noxious and destructive, than to acquire such asadd some kind of perfection, without which it is possible to sub-sist” (Art. CXXXVII) [1,15]. Furthermore, he maintains that sadnessis not in itself necessarily bad for the soul (contrary to the doctrinesof Stoicism, to which attempts have been made to associate him)as it is what informs the soul of the ill it is suffering from.
5. Psychopathology in the Cartesian universe
According to the humor-based characterology used by mostRenaissance authors, and deal with most extensively by Huartede San Juan in his The Examination of Mens Wits, there are fourtypes of temperaments, which are the result of the combinationof the different humors: the sanguine, the choleric, the phlegmaticand the melancholic temperament. The latter is associated withsleep disorders, such as insomnia and nightmares, and stubbornbehavior.
On this point, Descartes differed from the classical writers andthe prevailing humoralist theories and provides a new explana-tion for human temperaments, by making animal spirits directlyresponsible for these “inclinations”, and for their properties in par-ticular; the amount, consistency and level of agitation (Art. 55 ofThe Treatise of Man). As a result, if the spirits are very agitated, theycreate promptness, diligence and desire, and otherwise, tranquility ofspirit; an abundance of them creates liberality, generosity and love;if their consistency is “strong and coarse”, they generate confidenceand courage; if they are uniform in “shape, force and size”, theylead to constancy; finally, if these qualities are lacking, this will leadto tardiness, restlessness, malice, timidity and ruthlessness. Descartesstates that the natural inclinations or temperaments depend on thecombination of these qualities, so that for example, the “sad humoris composed of tardiness and restlessness, and can be augmentedby malice and timidity”. However, from a pathological perspective,Descartes also made it clear that “whatever can cause any change inthe blood can also cause change in the spirits” (Art. 60 of The Trea-
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tise of Man) [1,16], such as digestive, hepatic, biliary or respiratorydisorders.
There is a clear psychosomatic aspect to Cartesian theories interms of the etiopathogeny of diseases [2,34]. Indeed, in a lettersent to princess Elizabeth of Bohemia dated 18 May 1645, Descartessays that “the most common cause of a low-grade fever [that shewas suffering] is sadness” [1,4, p. 12]. Descartes was aware of thepersonal misfortunes that the princess had suffered, and in his let-ter he recommended that as well as conventional treatment, heshould free her mind of sad thoughts. At this point, it should alsobe mentioned that Descartes himself had experienced the effectsof depression. After graduating in law, as a young student he hadsuffered from depression and an identity crisis, which led him toquestion the theoretical value of his marvelous education, whichwas of hardly any use to him in real life. At that point, Descartesdid not know in which direction to focus his personal and pro-fessional life and withdrew into himself. His anxiety to discoverthe world and his physical laws with his own eyes and using hisown discernment was what enabled him to overcome his depres-sion, when he was 22 years old [60]. The French philosopher mayhave suffered from another episode of depression in his adult life,after the early death of his daughter Francine, at 5 years old, aftercontracting scarlet fever.
Descartes explained other psychopathological disorders, such asphobias, from the same psychosomatic perspective, when he sug-gested that the “strange aversions of some, who cannot endure thesmell of roses, the sight of a cat, or the like, come only from hence;that when they were but newly alive they were displeased withsome such like objects” (Art. CXXXVI of The Passions of the Soul)[1,15]. As a result, some authors have suggested that Descartes wasa type of pioneer in the field of psychoanalysis [22].
The only danger that passions can cause to the health lies intheir excess or misuse. Descartes proposed premeditation and skillas remedies for excesses of passions. Individuals should be able touse these to control the movements of the blood and the spiritsof thoughts which are linked to the passions. However, even withthese measures for fighting excesses in passions, “they aren’t suffi-cient to prevent bodily disorders; but they may suffice to preventthe soul from being troubled and losing its capacity for free judg-ment” (Letter to Princess Elizabeth of Bohemia, May 1646) [1,4, p.46]. Descartes thereby concludes his Treatise with an article enti-tled “That from them [the passions] alone all the good and evilof this life depends” (Art. CCXII), in which he says that wisdom“teaches us so to make ourselves masters of them, and managethem with so much dexterity, that the evils they cause may be easilyendured” [1,15]. When dealing with stress, it is essential to avoidingthinking about stressful things, while on the other hand, thinkingabout very pleasant situations and objects is very positive. As aresult, although Descartes did not systematize the psychosomatictheories in his philosophy, he was a pioneer in this field (a type ofprimitive cognitive-behavioral therapy). Unlike the theories of hisdetractors, the body and soul are closely linked in his theories, andact in unison.
Other remedies suggested by Descartes in his Treatise arehygienic or dietetic, taking into account that food is the basis ofall organic elements, including, of course, the animal spirits. As aresult, depending of the food consumed, the composition and con-sistency of the blood varies, so that when its consistency is “finer,”this will lead to joy, while if its consistency is “coarser”, its slowmovement will lead to sadness. Likewise, drinking spring watercould make it finer, while dry air makes the blood more subtle.Sleep and exercise enable the blood to nourish the substance of thebrain, making it more susceptible to the movement of the spirits.From another perspective, all these remedies stress the classicaltheories of illness as a consequence of an alteration in the balanceof the humors.
The pineal gland also plays a role in the French thinker’sphysiopathological explanations. In a letter to doctor LazareMeyssonnier (1611–1673), dated 29 January 1640, Descartes writesabout the relationship between the pineal gland and memory, andsuggests that the gland may be less mobile (with all the conno-tations that that entails) in people whose minds are “sluggish.”Likewise, in another letter written to father Mersenne two monthslater, he discusses the possibility of a decline in the functionality ofthis organ in human beings as a result of age.
6. The legacy of the Cartesian theories
The spirit of Cartesian physiology, which despite being inge-nious had the twin shortcomings of being excessively deductiveand not sufficiently experimental, is not limited merely to thework of Descartes and contemporaries. Indeed, it provided a frame-work and inspiration for the way man was understood throughoutthe entire 17th century (the iatromechanical and iatrochemicalcurrents) and conditioned much of the 18th century (the vitalistcurrent of the Enlightenment) [5,61]. By way of an example, someauthors continued to defend Descartes’ ideas in the 18th century,such as Claude-Nicolas Le Cat (1700–1768), who believed that the“material” that flowed in the nerves was not a known “material”(water, blood, vapor, electricity, light, fire, etc.), but was instead a“Universal Fluid”, that arose from the filtering of the blood in thecerebral cortex, where he believed the human soul was located [33].Likewise, Samuel-Auguste Tissot (1728–1797), in his renownedTraité des Nerfs (1784), undertook a detailed defense of the theoryof animal spirits. Similarly, the explanations of nerve function andtheir relationship to psychological phenomena by Charles Bonnet(1720–1793), a pioneer of 18th century mechanistic dualism, alsoowe much to Descartes, despite of the Swiss scientific scepticismconcerning animal spirits [30]. However, this theory was discardedas a result of the major breakthroughs in the field of microscopyand electrophysiology in the late 18th century. In 1780, Luigi Gal-vani (1737–1798) observed how the muscles of a frog contractedwhen an electrical current was applied to them, and in 1781 FeliceFontana (1730–1805) microscopically described the structure ofthe nerve fibers, thus confirming that the nerves were not hollow.Finally, our understanding of the way the brain and nervous sys-tem functions has changed for good since the mid-19th century,thanks to the rise of cellular biology and the histological disciplines.This process culminated in the late 1880s with the postulation ofneuronal theory by Santiago Ramón y Cajal (1852–1934) [39].
From the purely psychological perspective, the so-called “occa-sionalists” were the direct heirs to the Cartesian doctrine [7] andincluded the cleric Nicolas Malebranche (1638–1715), who triedto produce a symbiosis between Cartesianism and Augustianism.However, Baruch de Spinoza (1632–1677) was the most influen-tial critical heir of Cartesianism. Spinoza was a strict mechanicist,although unlike Descartes, he adopted a monist philosophical posi-tion, i.e. he rejected the existence of a body-soul dualism. Hethought that man was the sum of the body and mind, in the form ofa “universal substance” with infinite attributes, which could resem-ble both Nature and God (Deus sive Natura). This approach hasthe advantage compared to Cartesian theory of no communica-tion being necessary between the res cogitans and extensa in thepineal gland to explain human consciousness, as both attributes,like the passions and emotions, are “forms” of the same divine ornatural substance. There is an obvious determinism underlying thisexplanation, which Spinoza was unable to avoid.
Cartesian influence was also apparent in the specific field of psy-chopathology. The major influence of Descartes’ work on that ofWillis is striking. The latter, who benefited from the very favorableconditions for scientific study prevailing in Great Britain at that
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time, was able to perfect the Cartesian neurophysiological model.Willis, who ruled out the pineal gland as the location of the souland the seat of reason, believed that Descartes’ animal spirits were aconcept as classical as the “corporeal soul,” and that they were madeof light [62]. Likewise, he thought that melancholy was the conse-quence of a disorder in the brain and the animal spirits inside it.However, according to Willis, sadness and the trembling associatedwith the disorder arose from a cardiac dysfunction which corruptedthese spirits and made them dark, opaque, gloomy, instead of trans-parent, subtle and light [17]. These flows, which are in continuousmovement, led to a permanent agitation of thought when theyentered the brain and nervous system, which was responsible forsome of the symptoms of melancholy. Likewise, Archibald Pitcairn(1652–1713), founder of the Edinburgh School and one of the mostfervent advocates of iatromechanic thought based on the Cartesianphysiological theories, turned to a disorder of the blood hydrody-namics which affected the flow of animal spirits that circulated inthe nerves, leading to disordered and delirious thoughts in melan-choly [44]. The idea of a “slowing down” of this disorder is alsolinked with mechanistic philosophy, and related to the movementof fluids.
The influence of Cartesian “psychopathological” theories was sogreat that some authors continued to use these theories to explainthe origins of mental disorders even as late as the late 18th century.Among these authors was Johann Friedrich Meckel (1714–1774),who published an essay in the Mémoires de l’Académie Royale dePrusse in 1760, in which he maintained that psychoses were sec-ondary symptoms to an increase in the brain’s consistency whichlimited the free flow of animal spirits. Likewise, the theory pio-neered by Descartes on the role of the passions in the origin ofmental illnesses began to assume scientific importance at the endof the 18th century. This can be deduced from the comment by SirAlexander Crichton (1763–1856):
“The passions are to be considered, in a medical point of view,as part of our constitution, which is to be examined with theeye of the natural historian and the spirit and impartiality of aphilosopher. It is of no concern in this task [that of the doctor]to clarify whether these disorders should be esteemed naturalor unnatural, or moral or immoral. They are phenomena. thatcause beneficial or harmful effects on the faculties of the mind”[10, vol. 2, p. 97].
After the age of Descartes, madness gradually came to be seenas an abnormal way of associating ideas. This is apparent in thefact moral treatment that was predominant in 18th century psy-chiatry was based to a large extent on the importance attributedto the passions in the origin of mental disorders [45]. In fact, itwas based on manipulation of the emotions for therapeutic ends.One of its leading exponents, Philippe Pinel (1745–1826), said thatmelancholy consists of a false judgment that is formed by thepatient on the state of his body, which he believes to be endan-gered by trivial things, and fears that interests will be unsuccessful,and talks about a “depression of the spirit” [43]. During the 19thcentury, the role of the passions or emotions in psychopathol-ogy, either as a direct cause of diseases or as a consequence ofthem, became clearer. However, thanks to the major breakthroughsin the biological sciences that took place in the late 19th cen-tury, a process began, which has been called the “somatizationof mental illness”, in which madness came to be considered aresult of an organic injury and ceased to be thought of as theresult of a disorder in the sphere of the ideas and the passions[3,29]. Nonetheless, despite the triumph of these somaticist andbiologicist schools, which reached its height with the works byWilhelm Griesinger (1817–1868) and Emil Kraepelin (1856–1926),Descartes’ theory of the passions can be closely correlated with thetheories of emotions of contemporary authors (1924–2007). These
include the psychoanalytical theories of Hartvig Dahl (1924–2007),who also used the pairings of emotions model, and who in con-trast to the Cartesian “happiness–sadness” pairing, postulates the“happiness–depression” pairing [11].
7. Conclusions
Descartes is undoubtedly one of the most widely read and stud-ied philosophers in history, and can be considered one of thecornerstones of the scientific and intellectual revolution of the 17thcentury. According to George S. Brett, “dualism, atomism, ‘psychol-ogism’, introspectionism, intellectualism, mechanical physiology –these are the main legacies that Descartes left us” [7, p. 345]. How-ever, despite his enormous contributions, there is currently a schoolof thought that is critical of his legacy, and especially of its biologicalaspect. Among these are Antonio Damasio, who says in his popularbook Descartes’ Error.:
“It is paradoxical to think that Descartes, despite his contribu-tion to changing the course of medicine, helped to divert theorganismic, mind-in-the-body approach, which prevailed fromHippocrates to the Renaissance. How annoyed Aristotle wouldhave been with Descartes, had he known.” [12, p. 251].
However, despite the scientific foundations that Descartes usedto describe the functionalism of the human body being by any reck-oning rudimentary, and completely lacking the thoroughness thatmodern techniques and science demand for the positive assess-ment of a theory, the French philosopher’s intuitive perceptivenesswhen talking about the mechanisms of its functioning is remark-able when considered with the benefit of almost four centuries ofhindsight. On this subject, Sir Michael Foster (1836–1907), one ofthe great pioneers of modern physiology, commented that if weread between the lines of what Descartes wrote, we could substi-tute the terms “subtle fluid”, “animal spirits” or “system of tubeswith their valvular arrangements” by “molecular changes”, “ner-vous impulse” or “synaptic connexions” [20]. In this sense, theCartesian theories would not be so different from the one whichNeuroscience teaches us today.
But, what is beyond any doubt is that the Cartesian theorieson the passions and their role in the disorders of the mind out-lived their author by 200 years. While today we have dispensedwith Descartes’ philosophical ideas on the soul, we still continueto witness an astonishing similarity between the ideas of theFrench philosopher and the most recent discoveries in neuropsy-chophysiology and psychopathology. In fact, the modern conceptof “passion”, unlike that of “emotion”, is closely linked to the psy-chopathology of thought, in that it assumes a deformation (anovervaluation) of the subject’s ideas. In any case, the Cartesiandescription of sensory perception and the passions, including sad-ness, may be an unsettling premonitory metaphor for the scientificbreakthroughs that took place in the 20th century.
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