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This webpage reproduces a section of
Περὶ φυσικόν δυνάμεων
(On the Natural Faculties)


published in the Loeb Classical Library edition, 1916

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On the Natural Faculties

 p. ix  Introduction

Hippocrates and Galen. If the work of Hippocrates be taken as representing the foundation upon which the edifice of historical Greek medicine was reared, then the work of Galen, who lived some six hundred years later, may be looked upon as the summit or apex of the same edifice. Galen's merit is to have crystallised or brought to a focus all the best work of the Greek medical schools which had preceded his own time. It is essentially in the form of Galenism that Greek medicine was transmitted to after ages.

The Beginnings of Medicine in Greece. The ancient Greeks referred the origins of medicine to a god Asklepios (called in Latin Aesculapius), thereby testifying to their appreciation of the truly divine function of the healing art. The emblem of Aesculapius, familiar in medical symbolism at the present day, was a staff with a serpent coiled round it, the animal typifying wisdom in general, and more particularly the wisdom of the medicine-man, with his semi-miraculous powers over life and death.

"Be ye therefore wise as serpents and harmless as doves."

The Asclepiea or Health-temples.  p. x  The temples of Aesculapius were scattered over the ancient Hellenic world. To them the sick and ailing resorted in crowds. The treatment, which was in the hands of an hereditary priesthood, combined the best of the methods carried on at our present-day health-resorts, our hydropathics, sanatoriums, and nursing-homes. Fresh air, water-cures, massage, gymnastics, psychotherapy, and natural methods in general were chiefly relied on.

Hippocrates and the Unity of the Organism. Hippocrates, the "Father of Medicine" (5th to 4th centuries, B.C.) was associated with the Asclepieum of Cos, an island off the south-west coast of Asia Minor, near Rhodes. He apparently revitalized the work of the health-temples, which had before his time been showing a certain decline in vigour, coupled with a corresponding excessive tendency towards sophistry and priestcraft.

Celsus says: "Hippocrates Cous primus quidem ex omnibus memoria dignis ab studio sapientiae disciplinam hanc separavit." He means that Hippocrates first gave the physician an independent standing, separating him from the cosmological speculator. Hippocrates confined the medical man to medicine. He did with medical thought what Socrates did with thought in general — he "brought it down from heaven to earth." His watchword was "Back to Nature!"

At the same time, while assigning the physician his post, Hippocrates would not let him regard that post as sacrosanct. He set his face against any  p. xi tendency to mystery-mongering, to exclusiveness, to sacerdotalism. He was, in fact, opposed to the spirit of trade-unionism in medicine. His concern was rather with the physician's duties than his "rights."

At the dawn of recorded medical history Hippocrates stands for the fundamental and primary importance of seeing clearly — that is of clinical observation. And what he observed was that the human organism, when exposed to certain abnormal conditions — certain stresses — tends to behave in a certain way: that in other words, each "disease" tends to run a certain definite course. To him a disease was essentially a process, one and indivisible, and thus his practical problem was essentially one of prognosis — "what will be the natural course of this disease, if left to itself?" Here he found himself to no small extent in opposition with the teaching of the neighbouring medical school of Cnidus, where a more static view-point laid special emphasis upon the minutiae of diagnosis.

Observation taught Hippocrates to place unbounded faith in the recuperative powers of the living organism — in what we sometimes call nowadays the vis medicatrix Naturae. His observation was that even with a very considerable "abnormality" of environmental stress the organism, in the large majority of cases, manages eventually by its own inherent powers to adjust itself to the new conditions. "Merely give Nature a chance," said the father of medicine in effect, "and most  p. xii diseases will cure themselves." And accordingly his treatment was mainly directed towards "giving Nature a chance."

His keen sense of the solidarity (or rather, of the constant interplay) between the organism and its environment (the "conditions" to which it is exposed) is instanced in his book, "Airs, Waters, and Places." As we recognise, in our popular everyday psychology, that "it takes two to make a quarrel," so Hippocrates recognised that in pathology, it takes two (organism and environment) to make a disease.

As an outstanding example of his power of clinical observation we may recall the facies Hippocratica, an accurate study of the countenance of a dying man.

His ideals for the profession are embodied in the "Hippocratic oath."

Anatomy. Impressed by this view of the organism as a unity, the Hippocratic school tended in some degree to overlook the importance of its constituent parts. The balance was re-adjusted later on by the labours of the anatomical school of Alexandria, which, under the aegis of the enlightened Ptolemies, arose in the 3rd century B.C. Two prominent exponents of anatomy belonging to this school were Herophilus and Erasistratus, the latter of whom we shall frequently meet with in the following pages (v. p95 et seq.).

 p. xiii  The Empirics. After the death of the Master, the Hippocratic school tended, as so often happens with the best of cultural movements, to show signs itself of diminishing vitality: the letter began to obscure and hamper the spirit. The comparatively small element of theory which existed in the Hippocratic physiology was made the groundwork of a somewhat over-elaborated "system." Against this tendency on the part of the "Dogmatic" or "Rationalist" school there arose, also at Alexandria, the sect of the Empiricists. "It is not," they said, "the cause but the cure of diseases that concerns us; not how we digest, but what is digestible."

Greek Medicine in Rome. Horace said "Graecia capta ferum victorem cepit." Political domination, the occupation of territory by armies, does not necessarily mean real conquest. Horace's statement applied to medicine as to other branches of culture.

The introducer of Greek medicine into Rome was Asclepiades (1st century B.C.). A man of forceful personality, and equipped with a fully developed philosophical system of health and disease which commended itself to the Roman savants of the day, he soon attained to the pinnacle of professional success in the Latin capital: he is indeed to all time the type of the fashionable (and somewhat "faddy") West-end physician. His system was a purely mechanistic one, being based upon  p. xiv the atomic doctrine of Leucippus and Democritus, which had been completed by Epicurus and recently introduced to the Roman public in Lucretius's great poem "De Rerum Natura." The disbelief of Asclepiades in the self-maintaining powers of the living organism are exposed and refuted at considerable length by Galen in the volume before us.

The Methodists. Out of the teaching of Asclepiades that physiological processes depend upon the particular way in which the ultimate indivisible molecules come together (ἐν τῇ ποίᾳ συνόδῳ τῶν πρώτων ἐκείνων σωμάτων τῶν ἀπαθῶν) there was developed by his pupil, Themison of Laodicea, a system of medicine characterised by the most engaging simplicity both of diagnosis and treatment. This so‑called "Methodic" system was intended to strike a balance between the excessive leaning to apriorism shown by the Rationalist (Hippocratic) school and the opposite tendency of the Empiricists. "A pathological theory we must have," said the Methodists in effect, "but let it be simple." They held that the molecular groups constituting the tissues were traversed by minute channels (πόροι, "pores"); all diseases belonged to one or other of two classes; if the channels were constricted the disease was one of stasis (στέγνωσις), and if they were dilated the disease was one of flux (ῥύσις). Flux and stasis were indicated respectively by increase and diminution of the natural secretions;  p. xv treatment was of opposites by opposites — of stasis by methods causing dilatation of the channels, and conversely.

Wild as it may seem, this pathological theory of the Methodists contained an element of truth; in various guises it has cropped up once and again at different epochs of medical history; even to‑day there are pathologists who tend to describe certain classes of disease in terms of vaso-constriction and vaso-dilatation. The vice of the Methodist teaching is that it looked on a disease too much as something fixed and finite, an independent entity, to be considered entirely apart from its particular setting. The Methodists illustrate for us the tyranny of names. In its defects as in its virtues this school has analogues at the present day; we are all acquainted with the medical man to whom a name (such, let us say, as "tuberculosis," "gout," or "intestinal auto-intoxication") stands for an entity, one and indivisible, to be treated by a definite and unvarying formula.

To such an individual the old German saying "Jedermann hat am Ende ein Bischen Tuberkulose" is simply — incomprehensible.

*   *   *   *   *   *

Galen. All the medical schools which I have mentioned were still holding their ground in the 2nd century A.D., with more or less popular acceptance, when the great Galen made his entry into the world of Graeco-Roman medicine.

 p. xvi  His Nature and Nurture. Claudius Galenus was born at Pergamos in Asia Minor in the year 131 A.D. His father was one Nicon, a well-to‑do architect of that city. "I had the great good fortune," says Galen,​1 "to have as a father a highly amiable, just, good, and benevolent man. My mother, on the other hand, possessed a very bad temper; she used sometimes to bite her serving-maids, and she was perpetually shouting at my father and quarrelling with him — worse than Xanthippe with Socrates. When, therefore, I compared the excellence of my father's disposition with the disgraceful passions of my mother, I resolved to embrace and love the former qualities, and to avoid and hate the latter."

Nicon called his son Γαληνός, which means quiet, peaceable, and although the physician eventually turned out to be a man of elevated character, it is possible that his somewhat excessive leaning towards controversy (exemplified in the following pages) may have resulted from the fact that he was never quite able to throw off the worst side of the maternal inheritance.

His father, a man well schooled in mathematics and philosophy, saw to it that his son should not lack a liberal education. Pergamos itself was an ancient centre of civilisation, containing, among other culture-institutions, a library only second in importance to that of Alexandria itself; it also contained an Asclepieum.

 p. xvii  Galen's training was essentially eclectic: he studied all the chief philosophical systems of the time — Platonic, Aristotelian, Stoic, and Epicurean — and then, at the age of seventeen, entered on a course of medical studies; these he pursued under the best teachers at his own city, and afterwards, during a period of Wanderjahre, at Smyrna, Alexandria, and other leading medical centres.

Returning to Pergamos, he received his first professional appointment — that of surgeon to the gladiators. After four years here he was drawn by ambition to Rome, being at that time about thirty-one years of age. At Rome the young Pergamene attained a brilliant reputation both as a practitioner and as a public demonstrator of anatomy; among his patients he finally numbered even the Emperor Marcus Aurelius himself.

Medical practice in Rome at this time was at a low ebb, and Galen took no pains to conceal his contempt for the ignorance, charlatanism, and venality of his fellow-practitioners. Eventually, in spite of his social popularity, he raised up such odium against himself in medical circles, that he was forced to flee the city. This he did hurriedly and secretly in the year 168 A.D., when thirty-six years of age. He betook himself to his old home at Pergamos, where he settled down once more to a literary life.

His respite was short, however, for within a year he was summoned back to Italy by imperial mandate. Marcus Aurelius was about to undertake an  p. xviii expedition against the Germans, who at that time were threatening the northern frontiers of the Empire, and he was anxious that his consulting physician should accompany him to the front. "Patriotism" in this sense, however, seems to have had no charms for the Pergamene, and he pleaded vigorously to be excused. Eventually, the Emperor gave him permission to remain at home, entrusting to his care the young prince Commodus.

Thereafter we know little of Galen's history, beyond the fact that he now entered upon a period of great literary activity. Probably he died about the end of the century.

Subsequent History of Galen's Works. Galen wrote extensively, not only on anatomy, physiology, and medicine in general, but also on logic; his logical proclivities, as will be shown later, are well exemplified in his medical writings. A considerable number of undoubtedly genuine works of his have come down to us. The full importance of his contributions to medicine does not appear to have been recognized till some time after his death, but eventually, as already pointed out, the terms Galenism and Greek medicine became practically synonymous.

A few words may be devoted to the subsequent history of his writings.

Byzantine Medicine. During and after the final break-up of the Roman empire came times of confusion and of social reconstruction,  p. xix which left little opportunity for scientific thought and research. The Byzantine Empire, from the 4th century onwards, was the scene of much internal turmoil, in which the militant activities of the now State-established Christian church played a not inconsiderable part. The Byzantine medical scholars were at best compilers, and a typical compiler was Oribasius, body-physician to the Emperor Julian (4th century, A.D.); his excellent Synopsis was written in order to make the huge mass of the Galenic writings available for the ordinary practitioner.

Arabian Medicine. Greek medicine spread, with general Greek culture, throughout Syria, and from thence was carried by the Nestorians, a persecuted heretical sect, into Persia; here it became implanted, and hence eventually spread to the Mohammedan world. Several of the Prophet's successors (such as the Caliphs Harun-al‑Rashid and Abdul-Rahman III) were great patrons of Greek learning, and especially of medicine. The Arabian scholars imbibed Aristotle and Galen with avidity. A partial assimilation, however, was the farthest stage to which they could attain; with the exception of pharmacology, the Arabians made practically no independent additions to medicine. They were essentially systematizers and commentators. "Averrois che il gran comento feo"2  p. xx may stand as the type par excellence of the Moslem sage.

Avicenna (Ebn Sina), (10th to 11th century) is the foremost name in Arabian medicine: his "Book of the Canon in Medicine," when translated into Latin, even overshadowed the authority of Galen himself for some four centuries. Of this work the medical historian Max Neuburger says: "Avicenna, according to his lights, imparted to contemporary medical science the appearance of almost mathematical accuracy, whilst the art of therapeutics, although empiricism did not wholly lack recognition, was deduced as a logical sequence from theoretical (Galenic and Aristotelian) premises."

Introduction of Arabian Medicine to the West. Arabo-Scholastic Period. Having arrived at such a condition in the hands of the Mohammedans, Galenism was now destined to pass once more to the West. From the 11th century onwards Latin translations of this "Arabian" Medicine (being Greek medicine in oriental trappings) began to make their way into Europe; here they helped to undermine the authority of the one medical school of native growth which the West produced during the Middle Ages — namely the School of Salerno.

Blending with the Scholastic philosophy at the universities of Naples and Montpellier, the teachings of Aristotle and Galen now assumed a position of supreme authority: from their word, in matters  p. xxi scientific and medical, there was no appeal. In reference to this period the Pergamene was referred to in later times as the "Medical Pope of the Middle Ages."

It was of course the logical side of Galenism which chiefly commended it to the mediaeval Schoolmen, as to the essentially speculative Moslems.

The Renascence. The year 1453, when Constantinople fell into the hands of the Turks, is often taken as marking the commencement of the Renascence. Among the many factors which tended to stimulate and awaken men's minds during these spacious times was the rediscovery of the Greek classics, which were brought to Europe by, among others, the scholars who fled from Byzantium. The Arabo-Scholastic versions of Aristotle and Galen were now confronted by their Greek originals. A passion for Greek learning was aroused. The freshness and truth of these old writings helped to awaken men to a renewed sense of their own dignity and worth, and to brace them in their own struggle for self-expression.

Prominent in this "Humanist" movement was the English physician, Thomas Linacre (c. 1460‑1524) who, having gained in Italy an extraordinary zeal for the New Learning, devoted the rest of his life, after returning to England, to the promotion of the litterae humaniores, and especially to making Galen accessible to readers of Latin. Thus the "De Naturalibus Facultatibus" appeared in London in  p. xxii 1523, and was preceded and followed by several other translations, all marked by minute accuracy and elegant Latinity.

Two new parties now arose in the medical world — the so‑called "Greeks" and the more conservative "Arabists."

Paracelsus. But the swing of the pendulum did not cease with the creation of the liberal "Greek" party; the dazzling vision of freedom was to drive some to a yet more anarchical position. Paracelsus, who flourished in the first half of the 16th century, may be taken as typifying this extremist tendency. His one cry was, "Let us away with all authority whatsoever, and get back to Nature!" At his first lecture as professor at the medical school of Basle he symbolically burned the works of Galen and of his chief Arabian exponent, Avicenna.

The Renascence Anatomists. But the final collapse of authority in medicine could not be brought about by mere negativism. It was the constructive work of the Renascence anatomists, particularly those of the Italian sky, which finally brought Galenism to the ground.

Vesalius (1514‑64), the modern "Father of Anatomy," for dissecting human bodies, was fiercely assailed by the hosts of orthodoxy, including that stout Galenist, his old teacher Jacques Dubois (Jacobus Sylvius). Vesalius held on his way, however, proving, inter alia, that Galen had been wrong  p. xxiii in saying that the interventricular septum of the heart was permeable (cf. present volume, p321).

Michael Servetus (1509‑53) suggested that the blood, in order to get from the right to the left side of the heart, might have to pass through the lungs. For his heterodox opinions he was burned at the stake.

Another 16th-century anatomist, Andrea Cesalpino, is considered by the Italians to have been a discoverer of the circulation of the blood before Harvey; he certainly had a more or less clear idea of the circulation, but, as in the case of the "organic evolutionists before Darwin," he failed to prove his point by conclusive demonstration.

William Harvey (1578‑1657). William Harvey, the great Englishman who founded modern experimental physiology and was the first to establish not only the fact of the circulation but also the philosophical laws governing it, is commonly reckoned the Father of Modern Medicine. He owed his interest to the movements of the blood to Fabricio of Acquapendente, his tutor at Padua, who drew his attention to the valves in the veins, thus suggesting the idea of a circular as opposed to a to-and‑fro motion. Harvey's great generalisation, based upon a long series of experiments in vivo, was considered to have given the coup de grâce to the Galenic physiology, and hence threw discredit upon the whole system of medicine associated therewith.

Modern medicine, based upon a painstaking  p. xxiv research into the details of physiological function, had begun.

Back to Galen! While we cannot sufficiently commend the results of the long modern period of research-work to which the labours of the Renascence anatomists from Vesalius to Harvey form a fitting prelude, we yet by no means allow that Galen's general medical outlook was so entirely invalidated as many imagine by the conclusive demonstration of his anatomical errors. It is time for us now to turn to Galen again after three hundred years of virtual neglect: it may be that he will help us to see something fundamentally important for medical practice which is beyond the power even of our microscopes and X-rays to reveal. While the value of his work undoubtedly lies mainly in its enabling us to envisage one of the greatest of the early steps attained by man in medical knowledge, it also has a very definite intrinsic value of its own.

Galen's Debt to his Precursors No attempt can be made here to determine how much of Galen's work is, in the true sense of the word, original, and how much is drawn from the labours of his predecessors. In any case, there is no doubt that he was much more than a mere compiler and systematizer of other men's work: he was great enough to be able not merely to collect, to digest, and to assimilate all the best of the work done before his time, but, adding to this the outcome of his own observations, experiments, and reflections, to present  p. xxv the whole in an articulated "system" showing that perfect balance of parts which is the essential criterion of a work of art. Constantly, however, in his writings we shall come across traces of the influence of, among others, Plato, Aristotle, and writers of the Stoic school.

Influence of Hippocrates on Galen Although Galen is an eclectic in the best sense of the term, there is one name to which he pays a very special tribute — that of his illustrious forerunner Hippocrates. Him on quite a number of occasions he actually calls "divine" (cf. p293).

"Hippocrates," he says, "was the first known to us of all who have been both physicians and philosophers, in that he was the first to recognise what nature does." Here is struck the keynote of the teaching of both Hippocrates and Galen; this is shown in the volume before us, which deals with "the natural faculties" — that is with the faculties of this same "Nature" or vital principle referred to in the quotation.

"The Natural Faculties." If Galen be looked on as a crystallisation of Greek medicine, then this book may be looked on as a crystallisation of Galen. Within its comparatively short compass we meet with instances illustrating perhaps most of the sides of this many-sided writer. The "Natural Faculties" therefore forms an excellent prelude to the study of his larger and more specialised works.

 p. xxvi  Galen's "Physiology". What, now, is this "Nature" or biological principle upon which Galen, like Hippocrates, bases the whole of his medical teaching, and which, we may add, is constantly overlooked — if indeed ever properly apprehended — by many physiologists of the present day? By using this term Galen meant simply that, when we deal with a living thing, we are dealing primarily with a unity, which, quâ living, is not further divisible; all its parts can only be understood and dealt with as being in relation to this principle of unity. Galen was thus led to criticise with considerable severity many of the medical and surgical specialists of his time, who acted on the assumption (implicit if not explicit) that the whole was merely the sum of its parts, and that if, in an ailing organism, these parts were treated each in and for itself, the health of the whole organism could in this way be eventually restored.

Galen expressed this idea of the unity of the organism by saying that it was governed by a Physis or Nature (ἡ φύσις ἥπερ διοικεῖ τὸ ζῷον), with whose "faculties" or powers it was the province of φυσιολογία (physi‑ology, Nature‑lore) to deal. It was because Hippocrates had a clear sense of this principle that Galen called him master. "Greatest," say the Moslems, "is Allah, and Mohammed is his prophet." "Greatest," said Galen, "is the Physis, and Hippocrates is its prophet." Never did Mohammed more zealously maintain the unity of the Godhead than Hippocrates and Galen the unity of the organism.

 p. xxvii  Galen's Physics. But we shall not have read far before we discover that the term Physiology, as used by Galen, stands not merely for what we understand by it nowadays, but also for a large part of Physics as well. This is one of the chief sources of confusion in his writings. Having grasped, for example, the uniqueness of the process of specific selection (ὁλκὴ τοῦ οἰκείου), by which the tissues nourish themselves, he proceeds to apply this principle in explanation of entirely different classes of phenomena; thus he mixes it up with the physical phenomenon of the attraction of the lodestone for iron, of dry grain for moisture, etc. It is noteworthy, however, in these latter instances, that he does not venture to follow out his comparison to its logical conclusion; he certainly stops short of hinting that the lodestone (like a living organ or tissue) assimilates the metal which it has attracted!

Setting aside, however, these occasional half-hearted attempts to apply his principle of a φύσις in regions where it has no natural standing, we shall find that in the field of biology Galen moves with an assurance bred of first-hand experience.

The Mechanical Physicists. Against his attempt to "biologize" physics may be set the converse attempt of the mechanical Atomist school. Thus in Asclepiades he found a doughty defender of the view that physiology was "merely" physics. Galen's ire being roused, he is not content with driving the enemy out of the biological camp, but must needs attempt also to  p. xxviii dislodge him from that of physics, in which he has every right to be.

The Anatomists. In defence of the universal validity of his principle, Galen also tends to excessive disparagement of morphological factors; witness his objection to the view of the anatomist Erasistratus that the calibre of vessels played a part in determining the secretion of fluids (p123), that digestion was caused by the mechanical action of the stomach walls (p243), and dropsy by induration of the liver (p171).

Characteristics of the Living Organism. While combating the atomic explanation of physical processes, Galen of course realised that there were many of these which could only be explained according to what we should now call "mechanical laws." For example, non-living things could be subjected to φορά (passive motion), they answered to the laws of gravity (ταῖς τῶν ὑλῶν οἰακιζόμενα ῥοπαῖς, p126). Furthermore, Galen did not fail to see that living things also were not entirely exempted from the operation of these laws; they too may be at least partly subject to gravity (loc. cit.); a hollow organ exerts, by virtue of its cavity, an attraction similar to that of dilating bellows, as well as, by virtue of the living tissue of its walls, a specifically "vital" or selective kind of attraction (p325).

As a type of characteristically we may take nutrition, in which occurs a phenomenon  p. xxix which Galen calls active motion (δραστικὴ κίνησις) or, more technically, alteration (ἀλλοίωσις). This active type of motion cannot be adequately stated in terms of the passive movements (groupings and re-groupings) of its constituent parts according to certain empirical "laws." Alteration involves self-movement, a self-determination of the organism or organic part. Galen does not attempt to explain this fundamental characteristic of alteration any further; he contents himself with referring his opponents to Aristotle's work on the "Complete Alteration of Substance" (p9).

The most important characteristic of the Physis or Nature is its τέχνη — its artistic creativeness. In other words, the living organism is a creative artist. This feature may be observed typically in its primary functions of growth and nutrition; these are dependent on the characteristic faculties or powers, by virtue of which each part draws to itself what is proper or appropriate to it (το οἰκεῖον) and rejects what is foreign (το ἀλλότριον), thereafter appropriating or assimilating the attracted material; this assimilation is an example of the alteration (or qualitative change) already alluded to; thus the food eaten is "altered" into the various tissues of the body, each of these having been provided by "Nature" with its own specific faculties of attraction and repulsion.

The Three Categories. Any of the operations of the living part may be looked on in three ways, either (a) as a δύναμις,  p. xxx faculty, potentiality; (b) as an ἐνέργεια, which is this δύναμις in operation; or (c) as an ἔργον, the product or effect of the ἐνέργεια.3

 p. xxxi  Galen's Method. Like his master Hippocrates, Galen attached fundamental importance to clinical observation — to the evidence of the senses as the indispensable groundwork of all medical knowledge. He had also, however, a forte for rapid generalisation from observations, and his logical proclivities disposed him  p. xxxii particularly to deductive reasoning. Examples of an almost Euclidean method of argument may be found in the Natural Faculties (e.g. Book III chap. i). While this method undoubtedly gave him much help in his search for truth, it also not unfrequently led him astray. This is evidenced by his attempt, already noted, to apply the biological principle of the φύσις in physics. Characteristic examples of attempts to force facts to fit premises will be found in Book II chap. ix, where our author demonstrates that yellow bile is "virtually" dry, and also, by a process of exclusion, assigns to the spleen the function of clearing away black bile. Strangest of all is his attempt to prove that the same principle of specific attraction by which the ultimate tissues nourish themselves (and the lodestone attracts iron!) accounts for the reception of food into the stomach, of urine into the kidneys, of bile into the gall-bladder, and of semen into the uterus.

These instances are given, however, without prejudice to the system of generalisation and deduction which, in Galen's hands, often proved exceedingly fruitful. He is said to have tried "to unite professional and scientific medicine with a philosophic link." He objected, however, to such extreme attempts at simplification of medical science as that of the Methodists, to whom diseases were isolated entities, without any relation­ships in time or space (v. p. xv supra).

He based much of his pathological reasoning upon  p. xxxiii the "humoral theory" of Hippocrates, according to which certain diseases were caused by one or more of the four humours (blood, phlegm, black and yellow bile) being in excess — that is, by various dyscrasiae. Our modern conception of "hormone" action shows certain resemblances with this theory.

Besides observation and reasoning, Galen took his stand on experiment; he was one of the first of experimental physiologists, as is illustrated in the present book by his researches into the function of the kidneys (p59 et seq.). He also conducted a long series of experiments into the physiology of the spinal cord, to determine what parts controlled movement and what sensibility.

As a practitioner he modelled his work largely on the broad and simple lines laid down by Hippocrates. He had also at his disposal all the acquisitions of biological science dating from the time of Aristotle five hundred years earlier, and reinforced by the discoveries in anatomy made by the Alexandrian school. To these he added a large series of researches of his own.

Galen never confined himself to what one might call the academic or strictly orthodox sources of information; he roamed the world over for answers to his queries. For example, we find him on his journeys between Pergamos and Rome twice visiting the island of Lemnos in order to procure some of the terra sigillata, a kind of earth which had a reputation for healing the bites of serpents and  p. xxxiv other wounds. At other times he visited the copper-mines of Cyprus in search for copper, and Palestine for the resin called Balm of Gilead.

By inclination and training Galen was the reverse of a "party-man." In the Natural Faculties (p55) he speaks of the bane of sectarian partizan­ship, "harder to heal than any itch." He pours scorn upon the ignorant "Erasistrateans" and "Asclepiadeans," who attempted to hide their own incompetence under the shield of some great man's name (cf. p141).

Of the two chief objects of his censure in the Natural Faculties, Galen deals perhaps less rigorously with Erasistratus than with Asclepiades. Erasistratus did at least recognize the existence of a vital principle in the organism, albeit, with his eye on the structures which the scalpel displayed he tended frequently to forget it. The researches of the anatomical school of Alexandria had been naturally of the greatest service to surgery, but in medicine they sometimes had a tendency to check progress by diverting attention from the whole to the part.

The Pneuma or Spirit. Another novel conception frequently occurring in Galen's writings is that of the Pneuma (i.e. the breath, spiritus). This word is used in two senses, as meaning (1) the inspired air, which was drawn into the left side of the heart and thence carried all over the body by the arteries; this has not a few analogies with oxygen, particularly as its action in the tissues  p. xxxv is attended with the appearance of the so‑called "innate heat." (2) A vital principle, conceived as being made up of matter in the most subtle imaginable state (i.e. air). This vital principle became resolved into three kinds: (aπνεῦμα φυσικόν or spiritus naturalis, carried by the veins, and presiding over the subconscious vegetative life; this "natural spirit" is therefore practically equivalent to the φῦσις or "nature" itself. (b) The πνεῦμα ζωτικόν or spiritus vitalis; here particularly is a source of error, since the air already alluded to as being carried by the arteries tends to be confused with this principle of "individuality" or relative autonomy in the circulatory (including, perhaps, the vasomotor) system. (c) The πνεῦμα ψυχικόν or spiritus animalis (animaψυχή), carried by longitudinal canals in the nerves; this corresponds to the ψυχή.

This view of a "vital principle" as necessarily consisting of matter in a finely divided, fluid, or "etheric" state is not unknown even in our day. Belief in the fundamental importance of the Pneuma formed the basis of the teaching of another vitalist school in ancient Greece, that of the Pneumatists.

Galen and the Circulation of the Blood. It is unnecessary to detail here the various ways in which Galen's physiological views differ from those of the Moderns, as most of these are noticed in footnotes to the text of the present translation. His ignorance of the circulation of the blood does not lessen the force of his general physiological conclusions  p. xxxvi to the extent that might be anticipated. In his opinion, the great bulk of the blood travelled with a to-and‑fro motion in the veins, while a little of it, mixed with inspired air, moved in the same way along the arteries; whereas we now know that all the blood goes outward by the arteries and returns by the veins; in either case blood is carried to the tissues by blood-vessels, and Galen's ideas of tissue-nutrition were wonderfully sound. The ingenious method by which (in ignorance of the pulmonary circulation) he makes blood pass from the right to the left ventricle, may be read in the present work (p321). As will be seen, he was conversant with the "anastomoses" between the ultimate branches of arteries and veins, although he imagined that they were not used under "normal" conditions.

Galen's Character. Galen was not only a man of great intellectual gifts, but one also of strong moral fibre. In his short treatise "That the best Physician is also a Philosopher" he outlines his professional ideals. It is necessary for the efficient healer to be versed in the three branches of "philosophy," viz.: (alogic, the science of how to think; (bphysics, the science of what is — i.e. of "Nature" in the widest sense; (cethics, the science of what to do. The amount of toil which he who wishes to be a physician must undergo — firstly, in mastering the work of his predecessors and afterwards in studying disease at first hand — makes it absolutely necessary that he should  p. xxxvii possess perfect self-control, that he should scorn money and the weak pleasures of the senses, and should live laborious days.

Readers of the following pages will notice that Galen uses what we should call distinctly immoderate language towards those who ventured to differ from the views of his master Hippocrates (which were also his own). The employment of such language was one of the few weaknesses of his age which he did not transcend. Possibly also his mother's choleric temper may have predisposed him to it.

The fact, too, that his vivisection experiments (e.g. pp49, 273) were carried out apparently without any kind of anaesthetisation being even thought of is abhorrent to the feelings of to‑day, but must be excused also on the ground that callousness towards animals was then customary, men having probably never thought much about the subject.

Galen's Greek Style. Galen is a master of language, using a highly polished variety of Attic prose with a precision which can be only very imperfectly reproduced in another tongue. Every word he uses has an exact and definite meaning attached to it. Translation is particularly difficult when a word stands for a physiological conception which is sanctuary now held; instances are the words anadosis, prosthesis, and prosphysis, indicating certain steps in the process by which nutriment is conveyed from the alimentary canal to the tissues.

 p. xxxviii  Readers will be surprised to find how many words are used by Galen which they would have thought had been expressly coined to fit modern conceptions; thus our author employs not merely such terms as physiology, phthisis, atrophy, anastomosis, but also haematopoietic, anaesthesia, and even aseptic! It is only fair, however, to remark that these terms, particularly the last, were not used by Galen in quite their modern significance.

Summary. To resume, then: What contribution can Galen bring to the art of healing at the present day? It was not, surely, for nothing that the great Pergamene gave laws to the medical world for over a thousand years!

Let us draw attention once more to:

(1) The high ideal which he set before the profession.

(2) His insistence on immediate contact with nature as the primary condition for arriving at an understanding of disease; on the need for due consideration of previous authorities; on the need also for reflection — for employment of the mind's eye (ἡ λογικὴ θεωρία) as an aid of that physical eye.

(3) His essentially broad outlook, which often helped him in the comprehension of a phenomenon through his knowledge of an analogous phenomenon in another field of nature.

 p. xxxix  (4) His keen appreciation of the unity of the organism, and of the inter-dependence of its parts; his realisation that the vital phenomena (physiological and pathological) in a living organism can only be understood when considered in relation to the environment of that organism or part. This is the foundation for the war that Galen waged à outrance on the Methodists, to whom diseases were things without relation to anything. This dispute is, unfortunately, not touched upon in the present volume. What Galen combated was the tendency, familiar enough in our own day, to reduce medicine to the science of finding a label for each patient, and then treating not the patient, but the label. (This tendency, we may remark in parenthesis, is one which is obviously well suited for the standardising purposes of a State medical service, and is therefore one which all who have the weal of the profession at heart must most jealously watch in the difficult days that lie ahead.)

(5) His realisation of the inappropriateness and inadequacy of physical formulae in explaining physiological activities. Galen's disputes with Asclepiades over τὰ πρῶτα ἐκεῖνα σώματα τὰ ἀπαθῆ, over the ἄναρμα στοιχεῖα καὶ ληρώδεις ὄγκοι, is but another aspect of his quarrel with the Methodists regarding their pathological "units," whose primary characteristic was just this same ἀπάθεια (impassiveness to environment, "unimpressionability"). We have of course p. xlour Physiatric or Iatromechanical school at the present day, to whom such processes as absorption from the alimentary canal, the respiratory interchange of gases, and the action of the renal epithelium are susceptible of a purely physical explanation.​4

(6) His quarrel with the Anatomists, which was in essence the same as that with the Atomists, and which arose from his clear realisation that that primary and indispensable desideratum, a view of the whole, could never be obtained by a mere summation of partial views; hence, also, his sense of the dangers which would beset the medical art if it were allowed to fall into the hands of a mere crowd of competing specialists without any organising head to guide them.

The Author's Notes:

1 On the Affections of the Mind, p41 (Kühn's ed.).

2 "Averrhoës who made the great Commentary" (Dante). It was Averrhoës (Ebn Roshd) who, in the 12th century, introduced Aristotle to the Mohammedan world, and the "Commentary" referred to was on Aristotle.

3 What appear to me to be certain resemblances between the Galenical and the modern vitalistic views of Henri Bergson may perhaps be alluded to here. Galen's vital principle, ἡ τεχνικὴ φύσις ("creative growth"), presents analogies with l'Évolution créatrice: both manifest their activity in producing qualitative change (ἀλλοίωσις, changement): in both, the creative change cannot be analysed into a series of static states, but is one and continuous. In Galen, however, it comes to an end with the development of the individual, whereas in Bergson it continues indefinitely as the evolution of life. The three aspects of organic life may be tabulated thus:—

δύναμις ἐνέργεια ἔργον

Work to be done.

Work being done.

Work done, finished.

Future aspect.

Present aspect.

Past aspect.



The élan vital.

A changing which cannot be understood as a sum of static parts; a constant becoming, never stopping — at least till the ἔργον is reached.

A "thing."

"teleological" aspect.

"philosophical" aspect.

"outlook of physical science."

Galen recognized "creativeness" (τέχνη) in the development of the individual and its parts (ontogeny) and in the maintenance of these, but he failed to appreciate the creative evolution of species (phylogeny), which is, of course, part of the same process. To the teleologist the possibilities (δυνάμεις) of the Physis are limited, to Bergson they are unlimited. Galen and Bergson agree in attaching most practical importance to the middle category — that of Function.

While it must be conceded that Galen, following Aristotle, had never seriously questioned the fixity of species, the following quotation from his work On Habits (chap. ii) will show that he must have at least had occasional glimmerings of our modern point of view on the matter. Referring to assimilation, he says: "Just as everything we eat or drink becomes altered in quality, so of course also does the altering factor itself become altered. . . . A clear proof of the assimilation of things which are being nourished to that which is nourishing them is the change which occurs in plants and seeds; this often goes so far that what is highly noxious in one soil becomes, when transplanted into another soil, not merely harmless, but actually useful. This has been largely put to the test by those who compose memoirs on farming and on plants, as also by zoological authors who have written on the changes which occur according to the countries in which animals live. Since, therefore, not only is the nourishment altered by the creature nourished, but the latter itself also undergoes some slight alteration, this slight alteration must necessarily become considerable in the course of time, and thus properties resulting from prolonged habit must come to be on a par with natural properties."

Galen fails to see the possibility that the "natural" properties themselves originated in this way, as activities which gradually became habitual — that is to say, that the effects of nurture may become a "second nature," and so eventually nature itself.

The whole passage, however, may be commended to modern biologists — particularly, might one say, to those bacteriologists who have not yet realised how extraordinarily relative is the term "specificity" when applied to the subject-matter of their science.

4 In terms of filtration, diffusion, and osmosis.

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