as this, we see this taking into account of the dynamics of matter is fully exhibited, though presumably Plato is hostile to Democritus, for he never mentions him. Galen and the author of "The Nature of Man" take in this connection no account of it at all. We get at least a hint of it in "Ancient Medicine" which has more claim to being genuine. Indeed if Galen had commented on the elements of Hippocrates in this book he could not well have escaped the consideration of that point.

Aristotle had declared that essentially the doctrine of Empedocles was one of duality-that for him in reality there were two elements, force and matter. Galen does not pursue the discussion thus far; he only says if there were but one element no sense perception could arise. He thinks the impact of two atoms of the same substance in space could give rise to no quality. Indeed he seems to reject the whole atomic theory because of this apparent inefficiency in originating objective phenomena, since in its terms as familiar to him, "no atom is penetrable or capable of sensation."" At any rate this difficulty in the atomic theory for him seems to have been one of the things preventing him from accepting monism in cosmogony. He does not develop here the ground on which hist objection to it rests, but the inference is plain we only recognize the definition and limitation of matter, indeed the existence of matter at all, by the existence of its attributes or qualities, and these we apprehend through the existence of opposites. A thing is bitter because we know what is sweet, a thing is hot because we know what is cold. This was commonplace among philosophers, and Galen evidently did not consider it necessary to enlarge upon it. Manifestly, if there was only one element, an indivisible portion of matter, opposites could not exist in it and hence knowledge through the senses of matter in general could not arise. We need not stop to discuss this point of view. We can see by reference to the gibe I have quoted he must have thought the contribution of Protagoras to philosophy negligible. If the senses tell us nothing as to realities, he may have thought, they are at least all we have to rest on in cosmology. Most of the philosophers, Plato preeminently, refused to accept this, and we have now long bid farewell to the senses, before Einstein, as the limit of ascertainable knowledge. I cannot see that he reaches this level in philosophy at all. He remains at that of Herbert Spencer, who declared we must start with the knowable. This is all right for any one who knows what the knowable is, but it does not form a very solid basis for those, who, in Galen's words, possess only minds in which they have no confidence. Galen was a positivist, but I confess I am often at a loss in some of the phrases he uses involving this point, 4 Ibid., p. 421.

though we get a hint as to the origin of some of the narrow bias of his thought in this defence of the "Nature of Man." His pursuit of humoral doctrines in the practice of medicine led him astray. Not only, he says, would man be devoid of sensibility if there were only one element, but incapable of generation too, that being, we may suppose, also an apposition of contraries. Then, if there were only one element, there would be only one disease and one treatment. One may well doubt if the real Hippocrates or Plato or Aristotle ever reasoned with such loose ends as these, but obviously the turn of the argument is again a Spencerian one. In modern phraseology we would say a monistic homogeneity, a real monism, precludes the possibility that out of it heterogeneity can arise. I am not capable of passing judgment on this. I am only trying to trace out his thought in modern terms, and I am forced, in order thus to follow it logically in a modern view, to make some inferences which may be erroneous.

If he apparently falls short of the ancient viewpoint in this respect, and his repetitions serve to remind us of his embarrassment, in quoting them in their varying phraseology we get a suspicion he did not go the limits reached by Democritus and the older philosophers as to the possibilities of the ultimate division of matter. "If any one pricks the skin with the finest of needles, the animal suffers; the point touches only one or two or perhaps many atoms. First suppose only one is touched. No atom can be pierced and it is not susceptible of sense," etc. His mind almost sticks at the conception of the size of the point of the smallest needle and does not in any event arise to the contemplation of the minuteness of the division of matter nor of its energy demanded even by the ancient theory. Yet so common at Athens, 500 years before, was the conception of the vortex of atoms and their other mobilities that Aristophanes made fun of it on the stage. He finds difficulty, too, in imagining how out of senseless and impenetrable atoms sențiment and easily penetrable flesh can be formed at all. The vastness of the world of being lying between the ultimate atom and the proximate finger pulp his mind could not grasp, "for who will not wonder that flesh when pricked suffers, when its finest particles can not be pierced or made to suffer?"" I may be pardoned for lingering thus over the difficulties of a mind in many directions wonderfully acute though lacking that essential of all great minds, imagination, as exhibited in an author so influential as Galen in shaping the future thought of the world. It can not be denied that his mentality was in type that which is often referred to in modern parlance, perhaps not so much now as when positivism 5 Ibid., p. 436.

6 Ibid., p. 420.

7 Ibid., p. 423.

was at flood tide, as the only one for a man of science. I imagine we are to trace to an actual degeneration in the coordinating habit of the human intellect the sinking beneath the horizon of a conception of the cosmos as structurally beyond that furnished by the senses. It has had to be resurrected in our time before further advance could be made in a real knowledge of the fundamental facts of physical science. It was a conception familiar to Empedocles. I am not prepared to say if this submergence, after the great Greeks, is an anatomical, a dynamic or a social phenomenon of degeneration. It seems reasonable to think rather of the latter.

Monism, if not the whole atomic theory, being in Galen's view a doctrine incompatible with observed facts, he approaches a plurality of the elements with more caution than we might expect: "How many there are altogether is as yet undetermined. Therefore we will inquire into the matter." He finds other theoretical reasons, it is true, than the necessity for the supply of a sufficiently large enough variety of combinations, but as is well known he not only accepted the tetralogy of the elements, which Empedocles and his predecessors had presumably derived from Africa but he forced a host of phenomena, by means of the humoral doctrine, into the same narrow numerical confines. We will have to admit that in the then state of knowledge, the acceptation of earth, fire, water, air as elements was the most useful formula possible, however erroneous, for attacking the huge problems of physical science lying ahead of the human mind. Even from these some think "if they are sufficiently multiplied, varied, altered, transmuted, something may arise, which may be of another kind than that already existing." Aristotle, as has been noted, imputed the thought to Empedocles and at least all the modern systematist needs is two, that is, matter and energy, but it is obvious that the former without the latter is unworkable, however successful the modern monist may be in getting along only with the latter. Failing to take note. of the thought, evident at least in Aristotle, that energy may be regarded as an element in apposition to matter, really amounting to a dualism, we easily perceive Galen's inability to accept a monism. We have difficulties of our own. The modern human mind falters also, though, astounding as it seems, there are indications of modern man's belief in the possibility of breaking away from the human mind in cosmic theories, and this possibility Empedocles also seems to have played with, but such transcendentalism was not for Galen. However, I am plumbing the shallows of my own mind and ought not to speak for that of my congeners.

8 THE SCIENTIFIC MONTHLY, April, 1921.

9 Galeni de Elementis ex Hippocrate, Liber I, p. 428.

Galen reminds us of what seemed to him a quite obvious fact. The monist, whether ancient or modern, is, by virtue of his belief in a single element, a mutationist, a believer at least in the multiform aspects of a matter forced on our attention. That all the most ancient philosophers must have been, not only Heraclitus, who so strikingly phrased the idea, namely, that we never step twice in the same river, but Thales and all the rest. Manifestly earth, water, air and fire turning into one another has always been the only way for the monists to keep their doctrine in court. It is all one primordial substance, from which each is severally evolved, and when the argument takes a mystic turn this primordial substance may be unknown to us by our senses, or, out of one primordial element, water, for instance, the others are being continually evolved. The idea of Melissus1o that the whole universe is compounded of one immutable form of matter is too ridiculous. Aristotle as well as Hippocrates rejects this. It is not necessary to enter into the subtleties of the argument of Parmenides, but it is well to remember that if Plato did not stand in awe of him he respected him highly and portrays Socrates, despite his mock humility and sardonic humor, treating him with more real respect than he exhibits toward most antagonists. Parmenides defended this thesis in the abstract, and doubtless this was one of the reasons why by some historians he is said to have reduced the Eleatic philosophy to absurdities. At any rate Galen is in good company in refusing to accept the ideas of Melissus as worthy of discussion, but when he attempts to give some explanation for the origin of the qualities, he stumbles and falters even in his attack on Athenæus Attalensis, who defended the idea that the qualities were elements, an idea on all fours with the frequent lapse we seem to note in ancient arguments when they treat abstract conceptions as material realities. Moisture in the highest degree as an attribute of matter is water; the hottest heat the ancient knew was fire. In fact, the latter exists before fire, and from it fire is generated when great heat is introduced into fuel.

Under the terms of the argument as they appear in the account of Galen we might think it was a drawn battle, for when dryness and moisture were harnessed up with the other two (earth and air) elements, something else might be deduced. Dryness it would be hard to make into earth, however complete, and coldness could hardly have turned into air. There the facile illustration might have been balked, it would seem to a modern, but that was not the trend of Galen's refutation. We can refuse to believe either was right, but neither is that the point of interest for us. Under what

10 Ibid., p. 447.

11 Ibid., p. 457.

aspects could such doctrine be presented by either side to the controversy with such force as to satisfy any ancient mind that it was an explanation of cosmic philosophy? One of Galen's home thrusts is that cold disappears when heated and the dry when moistened. To us this seems proof sufficient that there is no such thing as the cold or the dry, just as Protagoras had pointed out by non-experimental methods, but this was not for Galen. I doubt if any one generation can ever throw light into all the blind alleys of the workings of the human mind in a former age. In some long gone past, when the doctrine of opposites was a fruitful theory we may conjecture some philosopher, seeking to extend its field of usefulness, pressed the opposites of cold and dry into service and they remained fixed in men's minds for thousands of years. We see Galen close to the path that the hot and the cold are but man's evolved reactions to degrees and kinds of molecular motion. It is true we have no reason to marvel that he did not see it all, but that he should not have stepped out of the path of error and into the path of truth after the early Greeks had shown that man arbitrarily makes himself the measure of the qualities of all things, creates them indeed, is reason for reflection on the imbecility of the human mind. That a part of the difficulty is the fault of the inadequacy of language to express human thought, of which it is called the vehicle, is quite probable. There are all sorts of nouns according to the rules of grammar, some substantive, some abstract, some generic, etc. Ancient thought tended to confuse not only the quality, the adjective, with them, but as moisture was the watery, so white tended to become whiteness and moisture at times became as substantive as water. How much this was a confusion of thought and how much it was a verbal confusion, it is not always easy to discern. There is a book,12 evidently spurious, attributed to Galen in which we come in full view of these difficulties where according to the title the discourse is about what qualities are corporeal, but we meet with the awkwardness which becomes an actual aberration of thought even in this book on the elements of Hippocrates and in the genuine treatise against Lycus.13

For the most part, however, Galen was aware and critical of this pitfall of ancient thought, though he seems occasionally to fall into it himself, for Galen's idea at times seems to be that heat and humidity can differ just as color or pleasure do. The fire may be made from wood or from straw and thus it differs. This throws the modern mind into panic and confusion, and we can not forbear seeing a source of error in such divagations. In his strug12 Galeno adscriptus liber quod qualitates incorporeal sint, Liber XIX, p. 463.

13 Galeni adversus Lycum libellus, Liber XVIII A, p. 196.