Medicine

The writings gathered under the name of Hippocrates take disease to arise from natural causes: from diet, from climate, from water and wind, and from the constitution of the body itself. Where healing had been a priestly office, the physician appears here as a craftsman, a practitioner of an art whose authority rests upon observation and experience rather than upon revelation. The treatise on the sacred disease argues that epilepsy, reputed the most divine of ailments, is no more sacred than any other, and that those who call it sacred do so from ignorance, concealing their inability to help behind the name of divinity. What follows from this position is a discipline possessing its own standards of evidence, one whose claims may be accumulated across generations because they are anchored in regularities that can be observed and compared.

The Hippocratic art is chiefly an art of regimen. In On Ancient Medicine the origin of the art is traced to the discovery of a diet suited to the sick, as the older discovery had been of a diet suited to men in health, and the physician who found out the one is said to stand in the same relation to his patients as the first cook stood to mankind. Drugs perform an auxiliary function. Surgery stands last among the means of the art, since there is an element of violence in it which accords ill with an art whose office is to cooperate with nature rather than to operate upon it. Medicine consists, the writer says, in three things: the disease, the patient, and the physician; and the patient must combat the disease along with the physician, who is himself the servant of the art.

The collection also sets forth the two kinds of knowledge the physician requires. He must know disease in general, so that maladies may be classified by their causes, their symptoms, and the course each typically runs; and he must know the patient as an individual, together with the circumstances of his life. The Book of Prognostics enumerates the signs by which an illness may be recognized and its issue foretold, while the treatise on the epidemics records the particular case histories from which such generalizations are drawn. Since no general rule fits all cases alike, the practice of the art requires prudence born of experience. It is the man, and not merely the disordered part, whom the physician is to examine: his habits and occupation, his manner of speech and his silences, his sleep and sometimes his dreams.

The question whether disease has natural causes was in this way separated from the question of what those causes are, and upon the second the tradition divided. Plato holds that the condition of the soul bears upon the body's condition; Galen answers with the humours and their proportions; Descartes maintains that the body is a machine whose disorders are mechanical throughout. Each accepts the Hippocratic premise while disputing what a natural account of disease must contain. The Oath, for its part, gave the profession the first explicit statement of the obligations its members assume toward those they treat, a matter considered further under the idea of Duty.

Plato treats the physician's art as the standard instance of an art which aims at the good of the thing in its care. In the Gorgias medicine is distinguished from cookery as a genuine art is distinguished from a knack that flatters: the one pursues health by means sometimes unpleasant, the other pursues gratification and takes no account of what is best. The same distinction is then carried over to the soul, where justice and legislation stand to the soul as medicine and gymnastic stand to the body. Whether the analogy holds only in proportion, or extends to the nature of the two arts themselves, is a question the dialogues raise more than once, and it recurs wherever the ruler is described as a physician of the city.

In the third book of the Republic Socrates argues that a well ordered city will have little need of elaborate medicine, since citizens reared upon a proper gymnastic and music will for the most part be healthy. Asclepius, he holds, treated wounds and acute illnesses but declined to prolong the lives of those whose bodies were diseased through and through. A multitude of physicians and lawcourts is on this view a sign that the city has failed at some earlier point, health being better secured by the ordering of life than by remedies applied afterward. The Laws adds a further distinction, between the physician who attends slaves and the physician who attends free men. The first prescribes what mere experience suggests and issues his orders like a tyrant; the second inquires into the nature of the disorder, converses with the patient and his friends, instructs him so far as he is able, and will not prescribe until he has persuaded him.

The Timaeus supplies the physiological doctrine which the earlier dialogues leave unstated. The body is compacted of four natures, earth and fire and water and air, and the unnatural excess or defect of these, or the passage of any one of them out of its own place, produces disorders and diseases. Plato then considers the ailments which arise from excess or defect among the humours. The account does not stop with the body, for the condition of the soul is held to affect the body's condition, and certain disorders of the soul are themselves referred to bodily causes, so that the two orders of ill are treated as continuous. The analogy between disorder in the body and disorder in the city is treated more fully under the idea of Justice.

Plato leaves to the tradition the conviction that medicine cannot be considered apart from ethics and politics. Aristotle takes up the comparison of medicine with the other arts and refines it; Aquinas repeats the doctrine that the healing art assists a nature which is the principal agent; and the language of modern psychiatry, when it speaks of the well balanced or integrated personality, appeals as Plato does to harmony as the principle of health. In this tradition the question how to heal is nowhere wholly separable from the question how to live.

Aristotle, whose father practiced medicine, ranks the healing art among those arts which imitate and cooperate with nature rather than among those which produce what nature by itself would never bring about. Health is the natural condition of a living body, the state toward which the organism's own principles tend, and the physician does not make health as the builder makes a house. He removes what obstructs the body's motion toward its proper balance, and the result comes about through nature's agency. Plants grow without farmers and men often recover without physicians, though less surely than with them, whereas shoes and houses are not produced at all without the shoemaker and the builder. Placing medicine among the cooperative arts in this way sets limits upon what the art may claim to accomplish.

In the Nicomachean Ethics health recurs as the standard example of a mean between extremes. Food and exercise in excess or in defect alike destroy health, while the due amount preserves it, and the moral virtues are said to stand in the same relation to the vices which flank them. The parallel is not merely illustrative. Medicine and ethics both deal with particulars which no universal rule exhausts, so that in each the agent must judge the case before him rather than apply a formula to it. For this reason, Aristotle holds, precision is not to be demanded of every subject alike, but only so far as the nature of the subject admits, and the good physician resembles the prudent man rather than the geometer.

The opening book of the Parts of Animals asks what standards the student of nature should employ, and whether the parts of animals are to be explained by the matter of which they are composed or by the function each performs. Aristotle decides for function. The anatomist must know the end for the sake of which a part exists, as the physician must know why a remedy works and not merely that it works. Medicine accordingly borders upon natural philosophy at one edge, the physician taking his principles from the student of nature, and upon prudence at the other. How far the physician must follow the philosopher, and where the province of the one ends and that of the other begins, is a question treated further under the idea of Art.

Aristotle's requirement that medicine rest upon a philosophy of nature was adopted by Galen, and with it the doctrine of final causes which governs Galen's anatomy and his polemic against the atomists. The requirement cut in both directions. When the Aristotelian philosophy of nature came to be questioned, the medicine erected upon it was questioned along with it, and Bacon and Descartes argued that the inherited errors could be removed only by beginning the inquiry afresh. Whether medicine can be reformed without a prior reform of natural philosophy remains among the disputed questions of the tradition.

Galen brings the Hippocratic and the Aristotelian doctrines into a single system, which governed the practice of medicine in the West and in Islam for more than a thousand years. The body, on his account, performs its operations by natural faculties: attraction draws the nourishment toward the organ, retention holds it there, alteration converts it into the organ's own substance, and expulsion casts out what is foreign or useless. These faculties are not occult powers but principles by which observable operations are explained, and Galen holds that their working may be traced by dissection and by experiment. He conducted anatomical investigations without number, upon animals if not upon men, and maintains that the physician who is ignorant of anatomy works in the dark.

Health, for Galen, consists in the right mixture of the four humours, blood and phlegm and the two biles, and disease consists in their disproportion. This is the Hippocratic doctrine systematized and supplied with physiological detail. In the dispute between the empirics, who relied upon trial and recollection without inquiring into causes, and the dogmatists, who reasoned from principles without submitting their conclusions to observation, Galen takes neither side entirely; the physician worthy of the name joins reason to experience. Much of his polemic is directed against the followers of Epicurus, and against Asclepiades and Erasistratus, who regarded the body as a piece of machinery and its disorders as displacements among corpuscles. Against them Galen argues that the living body is an organic unity and not an aggregation of atoms.

Nature herself, in Galen's phrase, is the artist, and nothing is done by her in vain. Every organ has its function and every structure its end, and this conviction, taken from Aristotle, supplies at once a principle of physiological research and a rule for the medical art, since the true art borrows its method from nature's own. The same conviction underlies his defense of general practice against the specialists. To treat the disordered part as though it could be separated from the living whole is, he holds, the consequence in practice of atomism in theory. The doctrine of final causes has also been charged with making his system resistant to correction, since an apparent anomaly could always be referred to some purpose not yet discovered.

Harvey, attentive as Galen was to the relation between structure and function, and asking always what purpose an organ serves, arrived by Galen's own principle at the circulation of the blood which Galen had missed. The authority of the Galenic writings came in time to obstruct the inquiry they had begun, and both Bacon and Descartes define their medical hopes partly in opposition to them. The ambition itself, that medicine should rest upon a systematic knowledge of the body's workings, is Galen's. Whether nature acts for ends, and what such action would require, is treated more fully under the idea of Cause.

Aquinas receives the Aristotelian and Galenic account of medicine and places it within a theological order. Medicine is a genuine art, subordinate to natural philosophy as natural philosophy is subordinate to theology. The physician works with the body's own form and with its inherent tendency toward health, and his interventions succeed only so far as they cooperate with that tendency. God is the first cause of health as of all else, but the secondary causes in nature act with an efficacy of their own, so that the physician is not a mere instrument of the divine will. He exercises skill and judgment within an order which has been established for him and which he does not create.

The Summa states the relation of art to nature in healing with unusual precision. Health is caused in a sick man sometimes by an exterior principle, namely the medical art, and sometimes by an interior principle, as when a man is healed by the force of nature. Just as nature heals by alteration, by digestion, and by the rejection of the matter which caused the sickness, so does art. The exterior principle acts not as the primary agent but as helping the primary agent, furnishing it with instruments and assistance of which the interior principle makes use in producing the effect. From this Aquinas draws the comparison, which recurs in his account of teaching, between the physician and the teacher: each brings exterior help to a process whose principal cause lies within the patient or the learner.

Health is further described as a disposition of the body, a habit in the broad sense, and disease as the corruption of that disposition. The parallel with the habits of the soul is more than a figure of speech, since soul and body are held to compose a single substance, so that what affects the one affects the other; the intemperate man injures his body along with his soul. From the same doctrine Aquinas derives the limits of the physician's obligation. He is bound to treat the sick, but not bound to employ every means of prolonging life, bodily life being a good, though not the highest good. Whether health is desirable for its own sake or for the sake of something further is discussed under the idea of Good and Evil.

Aquinas leaves the medieval world a conception of medicine at once respected and bounded: a knowledge of real causes, exercised by an art whose office is to assist nature, and operating within an order which sets both its purposes and its limits. Bacon, who complains that medicine has accepted its inherited limitations too readily, writes against a tradition in which the subordination of art to nature had received this precise formulation. Whether the physician's office is thereby restricted or merely described is a question on which the two men differ.

Bacon's quarrel with the medicine of his day is a quarrel about method rather than about the capacity of the ancients. Physicians, he holds, had reasoned from insufficient evidence, raising elaborate systems upon a few ill recorded observations and then defending those systems against new facts by dialectical ingenuity. What the art requires is induction: observations systematically gathered, cases compared with one another, remedies tried under conditions which allow the trial to be judged. Bacon proposes, in effect, that medicine be made an experimental science. He ranks it high among the sciences from which fruit is to be looked for, since on his view knowledge which yields no works stands under suspicion, and no work touches men more nearly than the recovery of health.

In the Advancement of Learning he surveys the state of medicine and finds it deficient in three respects. The preservation of health has been less studied than the cure of disease. The prolongation of life has been left to fable rather than taken up as a proper object of inquiry. The relief of pain, which he counts among the physician's offices even toward those beyond cure, has not been pursued with rigor. Each charge is directed at what Bacon takes to be the conservatism of the Galenic tradition, its readiness to accept the limits it has inherited. He recommends besides that physicians keep faithful narratives of the cases they treat, including those in which the cure failed, and that anatomy be pursued by comparison of many bodies rather than upon a single type.

Behind these particular complaints lies a general doctrine about the relation of knowledge to use. Nature is commanded only by being obeyed, and the measure of an understanding of nature is the operation which that understanding makes possible. Whether outcomes are a sufficient test of a theory, and whether the physician may be blamed for failures in an art which Bacon himself calls conjectural, are questions his account raises without settling. He grants that medicine is more subject to fortune than most arts, that its successes are ascribed to the physician and its failures to the disease, and that this uncertainty has been made an excuse for negligence rather than a spur to inquiry.

Bacon altered no practice and discovered no remedy. He set out the program which the following centuries carried through: observation, experiment, accumulated record, and the refusal to defer to authority where the evidence points elsewhere. Descartes takes up the same ambition and gives it a mechanical foundation, while Locke, who practiced the art Bacon described, questions how far its knowledge can ever pass from probability to demonstration. The relation between knowing nature and commanding it is treated more fully under the ideas of Science and Experience.

Descartes conceives the body as a machine, an automaton of extended matter, operating by the same laws which govern bodies of every other sort. Digestion is a kind of fermentation, the motion of the blood a matter of heat and of hydraulics, the action of the nerves the passage of animal spirits through small tubes. Nothing in the operations of the living body requires the vital forces, natural faculties, or substantial forms of the older physiology. Galen's attractions and retentions give place to mechanics, and the physician becomes one who diagnoses derangements in an instrument. The soul, on this account, is joined to the body without being the principle of its vital operations, a doctrine considered more fully under the idea of Soul.

In the sixth part of the Discourse Descartes declares the preservation of health to be the chief blessing and the foundation of all other blessings of this life, and it is on this ground chiefly that he urges the fruits to be expected from a completed physics. He grants that the medicine then in vogue contains little of remarkable utility, and observes that no one who professes it will deny that what men know is almost nothing beside what remains to be known. The prospect he holds out is that disease might come to be so far understood that the infirmities of age would be relieved and life extended. What separates present medicine from a perfect medicine is on this view a want of knowledge in physics and nothing besides.

The obstacle, as Descartes acknowledges, is the number and complication of the parts. No machine made by men contains arrangements so various, and the experiments needed to trace them exceed what a single inquirer can perform or pay for, so that in the same passage he asks the assistance of others in the work. He proposes accordingly that the causes be sought in the changes which experience shows to take place in the body, and that anatomy and physiology advance by steps toward the certainty he believes attainable in principle. Whether an art whose object is a machine of this complexity can ever be reduced to demonstration is a question he leaves open, and one his successors did not leave alone.

Descartes bequeaths to modern medicine a doctrine which proved fertile for anatomy and physiology, together with a difficulty the tradition has continued to press. Locke, himself a physician, replies that the inner constitution of bodies lies beyond our knowing, and that medicine must be content with probability. Freud, working upon disorders in which no lesion could be found, raises from the other side the question whether every disease is a disorder of the mechanism. How far mind and body interact in the origin and in the cure of illness is discussed under the idea of Man.

Locke studied medicine, worked with Thomas Sydenham, and practiced intermittently through his life, and the experience is visible in his account of the limits of human knowledge. Where Descartes had promised that a completed physics would yield a completed medicine, Locke holds that the inner constitution of bodies lies beyond demonstrative knowledge. We do not perceive the real essences of substances, the minute arrangements upon which the operations of the organs and the courses of diseases depend. What remains to us is experience: the observation of symptoms, the record of which remedies help and which do not, and the slow gathering of probable knowledge out of particular trials.

This is a limitation upon our faculties rather than a doubt about nature. Locke does not deny that the body acts by fixed laws; he denies that we can know those laws as we know the properties of figures and numbers. Medicine must therefore proceed case by case and hold its generalizations open to revision when new observations contradict them, and the physician who claims certainty where only probability is to be had does his patients a disservice. Sydenham's method, which classified diseases by their observable symptoms and by the course each typically runs rather than by conjectured causes, is the practice answering to this account of knowledge.

In the twelfth chapter of the fourth book of the Essay Locke sets out what natural philosophy may and may not accomplish. We may learn that certain remedies answer in certain cases without learning why they answer, and the distance between observing and explaining may never be wholly closed. He does not conclude from this that inquiry is idle. Experiments carefully made and faithfully reported enlarge the useful part of our knowledge even where science in the strict sense remains out of reach. The position moderates the expectations of Bacon and of Descartes without abandoning the empirical method both had urged. What degrees of assent are proper to knowledge of this kind is treated more fully under the idea of Opinion.

Locke's part in the history of medical thought is easily overlooked because it was so thoroughly absorbed. The practice of testing remedies by observed outcomes rather than by their agreement with theory follows the rule he laid down, and the classification of diseases by symptom and course, which he defended in Sydenham, survived the theories of causation that succeeded one another around it. Freud, taking up disorders whose causes could not be seen at all, appeals in his own manner to the discipline of recorded observation which Locke and Sydenham had made the physician's substitute for demonstration.

Freud began as a neurologist and continued to regard psychoanalysis as a branch of medicine, though its procedures departed from anything the profession had known. Neurotic symptoms, the paralyses without organic lesion, the obsessive acts, the anxieties without object, are on his view neither malingering nor moral fault but illness. They have causes, and the causes may be reached by a disciplined procedure. What has been repressed continues to operate outside consciousness and produces symptoms there, and the cure consists in making conscious what was unconscious. Whether disorders of functional origin are diseases in the same sense as those of somatic origin is a question which his work forced upon the tradition and which the tradition has continued to argue.

The extension of the medical model called for a change in what counts as a cause and in what counts as evidence. The causes Freud assigns, the wishes of childhood, the conflict between desire and prohibition, the mechanisms of repression and displacement, are shown by no instrument. They appear in speech: in free association, in dreams, in errors and slips of the tongue, in what the patient omits. The analyst attends to patterns which the patient cannot see. The method continues the older demand for observation, but the things observed are the involuntary productions of the mind rather than the visible signs of the body.

Freud's account of the relation between physician and patient returns psychotherapy to the main tradition of the healing art. The treatment presupposes an interest in psychological events and a sympathy with the patient, and it requires above all the patient's confidence, since the analysis leads to the most closely guarded of his thoughts. The patient must labor at his own cure, as the Hippocratic writer had said that the patient must combat the disease along with the physician. What the treatment aims at is the resolution of conflict and the restoration of harmony among the parts of the psyche, so that the norm of mental health is stated in terms not far from those in which Plato and Galen had stated the norm of bodily health.

Whether psychoanalysis falls within medicine or beside it has remained in dispute. Freud was aware that its therapeutic claims did not readily submit to experimental test, and its later doctrines concerning the structure of the psyche and the death instinct carry the theory well beyond what the clinical findings establish. The question he obliged the tradition to face, whether mental disorder is disease in the sense in which bodily disorder is disease, joins the art of medicine to the account of the soul's parts and powers given under the ideas of Mind and Soul.