An internet resource developed by
Christopher D. Green
York University, Toronto, Canada
ISSN 1492-3173

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Primary Source Reading Suggestions for History of Psychology Courses

First posted 1 May 1999
Last revised 12 September 2006

One of the primary goals of the "Classics" web site is to encourage instructors of history of psychology courses to assign primary source reading to their students. Secondary textbooks are useful for giving general overviews and setting contexts, but they cannot replace reading the original words of important thinkers. Many instructors of history of psychology courses, however, do not know precisely where the key historical passages lie, or which ones would be appropriate (in terms of length and difficulty) to assign to their students. The problem is especially acute when it comes to philosophical works, with which psychology instructors, understandably enough, typically have little acquaintance. In an effort to alleviate this problem somewhat, I have provided below descriptions of some of the most significant philosophical works in the history of psychology, along with suggestions about passages which might be included in students' reading assignments. Many of them are available on-line, either on the "Classics" site proper, or on the "Links to Other Sites" page. These suggestions are by no means definitive, but I hope they provide a starting point for those who would like to assign primary source material, but feel unsure about where to begin. Suggestions for additions or changes to this list are more than welcome.
-- Christopher D. Green --

Plato: Meno; Republic, Book IV; Timaeus selections
The Meno begins with a search for the definition of virtue, but rapidly evolves into a discussion of the sources of people's beliefs and of knowledge, an eminently psychological topic. A case could be made for reading the whole of the Meno (the Penguin edition is 55 pp.), in which Socrates argues that all knowledge worthy of the name is innate, and that the psyche is immortal. For a shorter assignment one could begin at the passage in which Meno states his famous paradox: "And how will you enquire, Socrates, into that which you do not know?" (80d). Read through the example in which the slave boy is shown to innately understand the Pythagorean Theorem, and end where Socrates concludes "And if the truth of all things always existed in the soul, then the soul is immortal" (86b) (about 11 pp.). The Theaetetus (about 80 pp.), which is also about the natures of belief and knowledge, but written much later in Plato's life, provides an interesting counterpoint to the Meno. It contains the famous analogies of the quality of a mind to the purity of a block of wax (191), and of memory to an aviary (197).

The Republic is primarily about the structure of the ideal state, but the entire work runs off an analogy to the structure of the human psyche. Roughly, just as the psyche has an intellectual part, a "spirited" or "courageous" part, and a desiderative or appetitive part, so society has intellectual philosophers, brave soldiers, and acquisitive merchants and workers. Further, just as the "best" kind of person is one who is ruled by his or her intellect rather than by indignation or desire, so the "best" state is one ruled by wise philosophers rather than by pugnacious soldiers or greedy merchants and workers. Plato's account of the structure of the psyche is laid out most completely in the second half of Book IV (about 15 pp. in the Penguin edition).

The Timaeus is a cosmogony and cosmology, treating the origin and nature of the universe as a whole. There are many psychologically-relevant passages scattered throughout. Some of the most important are in subsections 4-14 (22 pp. in "Main Section I" of the Penguin edition), in which the presumed origins of the psyche and the body are described, as is the means of their coming together in humans. A theory of sensation is outlined in subsections 31-36 (8 pp. in "Main Section II"), but understanding it depends on some background in Plato's physics, given in subsections 22-30 (which might best be conveyed in lecture form prior to the reading assignment). Main Section III is mostly about physiology, but subsections 45-48 (about 5 pp.) cover topics more directly relevant psychology: diseases of the mind, the balance between mind and body, and both mental and physical health.

Good secondary sources include Thomas Robinson's Plato's Psychology, Erik Ostenfeld's Ancient Greek Psychology and the Modern Mind-Body Debate, Chapter 5 of Julia Annas' An Introduction to Plato's Republic, and Sabina Lovibond's "Plato's Theory of Mind" (in S. Everson's, Companions to Ancient Thought 2: Psychology.)

Aristotle: De Anima, Book II, chapters 1-6, 12; Book III, chapters 3-6.
These passages from De Anima give an overview of Aristotle's theory of the psyche. Chapter 1 of Book II argues for the psyche being the form (in Aristotle's sense) of the living body, rather than a kind of body in its own right. Chapters 2 and 3 describe the hierarchical relation between the "parts" or "functions" of the psyche: nutrition, perception, desire, movement, imagination, intellect. Chapter 4 covers the nutritive faculty, chapter 5 covers sensation in a general way, and Chapter 6 discusses the much-misunderstood "common sense" (i.e., that in which the impressions from the various individual senses are combined). Chapter 12 discusses kinds of sense objects, and includes the famous analogy between perception and an impression in a wax tablet. The suggested chapters from Book III discuss the imagination and the intellect (including the distinctions between the passive and active intellects, and between simple and complex ideas). In the Penguin edition of De Anima, all this totals about 25 pp.

In order to understand these readings, students will have to be given some background in Aristotle's metaphysics (particularly the analysis of substances into matter and form) and in his physics (particularly his account of causation). This can be gotten many places. One account of such issues can be found in chapter 4 of Early Psychological Thought: Ancient Accounts of Mind and Soul (C.D. Green & P.R. Groff, in press), especially the section entitled "Logic, metaphysics, and physics."

What I have not included: Book I of De Anima primarily consists in Aristotle's criticisms of his predecessors' theories of the psyche. Chapters 7-11 of Book II outlines each individual sense (sight, hearing, smell, taste, and touch). Chapters 1-2 of Book III are about special problems with perception, and chapters 7-11 are on the connection of the senses to the intellect, and about motivation.

Good secondary sources include the articles reprinted in Michael Durrant's Aristotle's De Anima in Focus, the articles in Martha C. Nussbaum and Amélie Oksenberg Rorty's Essays on Aristotle's De Anima, T. H. Irwin's "Aristotle's Philosophy of Mind" (in S. Everson's Companions to Ancient Thought 2: Psychology), and Stephen Everson's "Psychology" (in Jonathan Barnes' The Cambridge Companion to Aristotle).

As is well-known, the "Hippocratic Corpus" was not all written by Hippocrates of Cos, but rather by generations of physicians who followed him. The one Hipppocratic work probably most frequently mentioned in history of psychology textbooks is "On the sacred disease" (14 pp. in Penguin's Hippocratic Writings), in which it is argued that (what we now call) epilepsy is due to brain abnormalities rather than to divine intervention. It contains a particularly interesting description of Ancient views of the brain and its functioning. Also interesting is "On injuries of the head" (not in the Penguin ed., but would be ~16 pp.). Section 13 contains the famous observation that damage to one side of the head often causes disability in the opposite side of the body.

For an account of the belief that imbalance among the four humours causes disease, see the treatise known as "The nature of man" (~13 pp. in the Penguin ed., not available on-line). The Loeb Library volume entitled Hippocrates IV also contains a ~15 pp. treatise called just "Humours," (but it is neither in the Penguin ed., nor on-line, as far as I can tell). Another particularly interesting work is "On Ancient Medicine" (called "Tradition in Medicine" in the Penguin ed., ~17 pp.), which empasizes the importance of diet in the etiology and treatment of disease, and argues against the popular claim of the day that diseases are all caused by excessive heat, cold, wetness, or dryness. Finally, "The science of medicine" (~9 pp.), is a polemic against philosophers in which it is argued that medical knowledge is superior to philosophical knowledge. It is full of poor arguments, but it also shows that the Hippocratics were not the pure empiricists they are often claimed to be: "what escapes our vision we must grasp by mental sight... [we] must have rescourse to reasoning..."

Herophilus and Erasistratus (fl. ca. 300 BC) were first distinguish nerves from the circulatory system, and even sensory nerves from motor nerves, but their writings have been lost, and so their discoveries are reported in the works of others (e.g., Galen). Heinrich von Staden's Herophilus: The Art of Medicine in Early Alexandria (1989) is magisterial, and contains much of the testimonia about its subject in English translation. There is no equivalent work about Erasistratus.

Galen's On the Natural Faculties is the best-known of his works, but it is mainly about physiological, rather than psychological, topics. A good general discourse on the genesis of the humors can be found in Book II chapter 8, but much of it is occupied with arguments against Erasistratus, and so may not be appropriate for an introduction to Galen's thought. Most of his commentary on the structure and function of the brain are to be found in other works. On the Doctrines of Hippocrates and Plato is a long work arguing, on the side of those named in its title, that our "vital powers" have three sources: the brain, the heart, and the liver (contra the view of Aristotle and the Stoics that there is only one -- the heart). Book VII, Section 3 contains the argument that the psyche is housed in the "body of the brain," not in the ventricles, and describes some experiments to support this contention. It also describes the putative process by which "vital pneuma" in the blood is refined into "psychic pneuma" (later translated as "animal spirits") by being filterd through the "retiform network" of blood vessels in the head (that, it turns out, doesn't actually exist in humans, but does in pigs and cattle). On the Usefulness of the Parts of the Body (Book VIII, Sec. 10-14) contains and extensive discussion of the anatomy of the cerebral ventricles. Section 14 gives a particularly good account of the pineal gland, including a refutation of a position quite close to the one Descartes would adopt 1500 years later. It is interesting to note that, contrary to popular belief, he never locates the mental faculties (typically imagination, cognition, and memory) in the ventricles themselves, although his work clearly had a profound effect on those later philosophers who did. Another of Galen's works that might be of interest is his Commentary on Hippocrates' On the Nature of Man. A good, though somewhat "whiggish," secondary source is Rudolph E. Siegel's Galen on Psychology, Psychopathology, and Function and Diseases of the Nervous System (1973).

Unfortunately, very little translated Medieval work is on the web as yet. Exacerbating this problem considerably is the level of misinformation about the Middle Ages that permeates standard history of psychology textbooks. First and foremost, apart from a few celebrated cases, madness in the Middle Ages was not typically considered to be the result of the actions of witches or demons; it was usually regarded as being biological in origin (see, e.g., Spanos, N. P. (1978). Witchcraft in histories of psychiatry: A critical analysis and an alternative conceptualization. Psychological Bulletin, 85, 417-439). Indeed, the "great witch craze" did not even occur in the Middle Ages, as is almost universally believed by lay people, but in the Renaissance (see, e.g., Norman Cohn's Europe's Inner Demons).

Biological and theological theories of the mind and soul were closely connected during the Middle Ages. It has been suggested that Nemesius' Treatise on the Nature of Man (ca. 400, sometimes misattributed to Gregory of Nyssa) is the earliest still-extant desciption of Medieval ventricular theory (the belief that the mental faculties are housed in the ventricles of the brain) (see especially Sections 30-32). Augustine, however, in his On the Literal Meaning of Genesis (Book VII, chapter 18), clearly states that "the medical writers" were of the opinion that front ventricle "is the one from which all sensation comes," the middle one is "the seat of memory," and the posterior ventricle "is the one from which all motion comes." Although this does not reflect what would become the "canonical" ordering of the faculties in the ventricles, it is, perhaps, the earliest still-extant statement placing specific faculties in specific ventricles. Other early psychologically-significant works include Augustine's Treatise on the Soul and Its Origin, and the section of Augustine's Confessions on memory (Book X, chapters 8-23, ~15 pp.), both of which are on-line.

Many later Medieval scholars, of course, wrote on matters of the soul or anima. For some general background on Islamic philosophy (which reached its pinnacle earlier than did Western Medieval philosophy), there is a good, short, general article on Medieval Islamic philosophy -- including a concise passage on their interpretation of Aristotelian psychological thought -- in the Catholic Encyclopedia. Avicenna's commentary on Aristotle's De anima (Liber de Anima seu Sextus de Naturabilis) is among the most influential works of the Age, even among later Christian philosophers, but I have been unable to find an English translation of it. Avicenna's own summary of this material -- the Kitab al-najat -- has been translated by F. Rahman, however, in a 1952 book entitled Avicenna's Psychology. The main text runs about 45 pp. in length, chapter 3 contains the most direct statement of the "ventricular theory," and the final few chapters contain the most important Islamic departures from authentic Aristotelianism.

Important psychological works from the Western High Middle Ages include Albert the Great's De Anima, Thomas Aquinas' Sententia Libri de Anima, and Peter of Spain's (later Pope John XXI) Scientia Libri de Anima. One cannot ignore, of course, Thomas Aquinas' Summa Theologica, probably the single most influential work of the Middle Ages. The whole work is available on-line, and Questions 75-102 of the First Part contain an important discussion of the nature of the soul. Another work to consider is Roger Bacon's Opus Magnus, which contains an amazingly modern account of optics (derived, in part, from that of the Islamic scientist, Alhazen).

Good recent secondary sources include Simon Kemp's Medieval Psychology and Cognitive Psychology in the Middle Ages, Anthony Kenny's Aquinas on Mind, and Mary Carruthers' Book of Memory. One might also look at Robert Pasnau's Theories of Cognition in the Later Middle Ages, Joseph Owens' Cognition: An Epistemological Inquiry, and Basil Clarke's Mental Disorder in Earlier Britain.

René Descartes' Discourse on Method (1637) and Meditations on First Philosophy (1641) might well be regarded as "must" reading for all members of Western Civilization. Each runs about 70 pp. in length. Given the constraints of the typical history of psychology course, however, the Fourth Discourse (8 pp.) and the Second Meditation (11 pp.) are where he presents the famous cogito ergo sum argument. The Treatise on Man (written in 1633, Second Treatise of The World, ~70 pp.) contains Descartes' famous account of the hydraulics of bodliy movement (~10 pp.), including the oft-reproduced -- including just to the left here -- drawing of the motor reflex. In Descartes' final book, The Passions of the Soul (1649), he outlines the relation, as he saw it, between the mind and body, and presents his theory of the emotions.

Thomas Hobbes' Leviathan (1651) opens with a series of 16 chapters collectively entitled "Of Man." This part of the book runs about 100 pp., but a number of the most basic topics (sense, imaginiation, speech, reason, passions) are covered in the first six chapters (35 pp.). Much of the same material was covered by Hobbes about a decade ealier in Human Nature (first publised as Part I of Elements of Law, Natural and Politic, 1640).

John Locke's An Essay Concerning Human Understanding (1689-1691) is, of course, the founding document of British Empiricism. It is a wide-ranging, two-volume work. Locke's critique of innate ideas in contained in Book I, the first chapter of which, entitled "No innate speculative principles" (~27 pp.), gives a good overview of his objections. If one prefers to assign a statement of Locke's positive empiricist program, chapter 1 of Book II, "Of ideas in general and their original" (~23 pp.) is a good place to start. It is worth looking at chapter 2, "Of simple ideas," and chapter 12, "Of complex ideas," as well. Book III is about the meanings of words (names, in particular), and Book IV is about knowledge and reason. Both are historically important, but probably beyond the scope of the typical history of psychology course.

Gottfried Wilhelm von Leibniz's New Essays on the Human Understanding (1704) is a direct critique of Locke. The first chapter or two might be usefully assigned as a rationalist counterpoint to a Locke assignment. Chapter 1 of Book II contains the famous conclusion that nothing is in the mind that was not first in the senses, except for the mind itself. Leibniz's Monadology (1714) is mainly a metaphysical work, but contains some interesting psychological implications (taking the term fairly broadly).

George Berkeley's empiricism was more radical than Locke's. In Principles of Human Knowledge (1710), he argues for the eradication of Locke's distinction between primary and secondary qualities -- they are all secondary, and therefore dependent on our senses. In the first edition, he even goes so far as to claim that "in truth, the object and the sensation are the same thing" (§5). The first 21 sections (~12 pp.) give a good flavor of his argument. Berkeley's Essay Towards a New Theory of Vision (1709) gets a goods deal of play in some history of psychology textbooks, mainly because of the radically empiricist claim that we only learn to perceive distance visually by first exploring space via tactile means.

David Hume's Treatise of Human Nature (1739-1740) is second in importance, in the empiricist tradition, only to Locke's Essay. Part I of Book I (~25 pp.) contains Hume's basic theory of ideas and their association. Its first five sections (~15 pp.) alone would probably make a reasonable reading assignment, particularly if one wanted to include, as well, the key passages on Hume's famous theory of causation (viz., that we can know no more about it than the successive conjunction of events we observe), which are contained the first three sections of Part III of Book I (~13 pp.). Some of these ideas are summarized in Part I (~ 50 pp.) of the Enquiry Concerning Human Understanding (1748). Also, the last lines of Hume's Enquiry contain the immortal words: "When we take into our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: For it can contain nothing but sophistry and illusion."

Immanuel Kant's work is, of course, notoriously difficult. One place students might start is the Prolegomena to Any Future Metaphysics (1783), which is a relatively brief summary (~130 pp.) of the material laid out in the Critique of Pure Reason (1781/1787), which may well be the single most important philosophical work of the modern era. The opening sections of Part II (§§14-30, ~20 pp.) of the Prolegomena discuss the Categories of Mind. It is crucially important for students to bear in mind, however, that the Categories were not intended, by Kant, to describe a theory of psychology. They were, instead, regarded as the structures that make possible empirical science of any kind. (Although it is not of first importance to psychologists, it is important to remember that Kant's main aim here was to save Newtonian physics from the acid touch of Humean scepticism.) Kant was dubious that an empirical science of psychology was even possible (see the opening of the Metaphysical Foundations of Natural Science (1786) for some of his reasons). Before reading Part II of the Prolegomena, it might be wise for students to be familiarized with the material of the Prolegomena's Preamble (~15 pp.) first, as it lays out Kant's general aims. A work of Kant's that is ignored all too often is his Anthropology from a Pragmatic Point of View (1798). Its contents look very much like what we today would call an empirical psychology (indeed, Kant would agree, he just wouldn't have a regarded it as natural science, properly speaking): Book I is entitled "On the cognitive faculty" and contains sections on consciousness, sensation, perception, unconscious ideas, and intellience, among others. Book II is on pleasure and pain, and Book III on desire.

Secondary sources on Kant are often almost as difficult as the originals they attempt to elucidate. One might look at Gary Hatfield's "Empirical, Rational, and Transcendental psychology: Psychology as Science and as Philosophy," or Paul Guyer's "The Transcendental Deduction of the Categories," both in the Cambridge Companion to Kant (Paul Guyer, Ed.).