Alcmaeôn of Crotôn was in his prime at the beginning of the fifth century B.C.

He wrote a book on Natural Science.

1. Alcmaeon of Croton, son of Peirithous, said the following to Brotinus and Leon and Bathyllus: concerning things unseen, (as) concerning things mortal, the gods have certainty, whereas to us as men conjecture (only is possible).

Ia. Man differs from the other (creatures) in that he alone understands; the others perceive, but do not understand.

2. Men perish because they cannot join the beginning to the end.

3. (In mules, the males are sterile because of the fineness and coldness of the seed, and the females because their wombs do not open).

4. Health is the equality of rights of the functions, wet-dry, cold-hot, bitter-sweet and the rest; but single rule among them causes disease; the single rule of either pair is deleterious. Disease occurs sometimes from an internal cause such as excess of heat or cold, sometimes from an external cause such as excess or deficiency of food, sometimes in a certain part, such as blood, marrow or brain; but these parts also are sometimes affected by external causes, such as certain waters or a particular site or fatigue or constraint or similar reasons. But health is the harmonious mixture of the qualities.

5. It is easier to guard against an enemy than against a friend.

Early Greek Philosophy by John Burnet, 3rd edition (1920). London: A & C Black Ltd.

Alcmaeon of Croton

Aristotle tells us that Alkmaion of Kroton was a young man in the old age of Pythagoras. He does not actually say, as later writers do, that he was a Pythagorean, though he points out that he seems either to have derived his theory of opposites from the Pythagoreans or they theirs from him . In any case, he was intimately connected with the society, as is proved by one of the scanty fragments of his book. It began as follows: “Alkmaion of Kroton, son of Peirithous, spoke these words to Brotinos and Leon and Bathyllos. As to things invisible and things mortal, the gods have certainty; but, so far as men may infer . . .” The quotation unfortunately ends in this abrupt way, but we learn two things from it. In the first place, Alkmaion possessed that reserve which marks all the best Greek medical writers; and in the second place, he dedicated his work to the heads of the Pythagorean Society.

Alkmaion's importance really lies in the fact that he is the founder of empirical psychology. He regarded the brain as the common sensorium, a view which Hippokrates and Plato adopted from him, though Empedokles, Aristotle, and the Stoics reverted to the more primitive view that the heart is the central organ of sense. There is no reason to doubt that he made this discovery by anatomical means. We have authority for saying that he practised dissection, and, though the nerves were not yet recognised as such, it was known that there were certain “passages” (πόροι) which might be prevented from communicating sensations to the brain by lesions. He also distinguished between sensation and understanding, though we have no means of knowing where he drew the line between them. His theories of the special senses are of great interest. We find in him already, what is characteristic of Greek theories of vision as a whole, the attempt to combine the view of vision as a radiation proceeding from the eye with that which attributes it to an image reflected in the eye. He knew the importance of air for the sense of hearing, though he called it the void, a thoroughly Pythagorean touch. With regard to the other senses, our information is more [/195] scanty, but sufficient to show that he treated the subject systematically.

His astronomy seems very crude for one who stood in close relations with the Pythagoreans. We are told that he adopted Anaximenes' theory of the sun and Herakleitos's explanation of eclipses. If, however, we were right in holding that the Second Part of the poem of Parmenides represents the view of Pythagoras, we see that he had not gone very far beyond the Milesians in such matters. His theory of the heavenly bodies was still “meteorological.” It is all the more remarkable that Alkmaion is credited with the view that the planets have an orbital motion in the opposite direction to the diurnal revolution of the heavens. This view, which he may have learnt from Pythagoras, would naturally be suggested by the difficulties we noted in the system of Anaximander. It doubtless stood in close connexion with his saying that soul was immortal because it resembled immortal things, and was always in motion like the heavenly bodies. He seems, in fact, to be the author of the curious view Plato put into the mouth of the Pythagorean Timaios, that the soul has circles in it revolving just as the heavens and the planets do. This too seems to be the explanation of his further statement that man dies because he cannot join the beginning to the end. The orbits of the heavenly bodies always come full circle, but the circles in the human head may fail to complete themselves.

Alkmaion's theory of health as “isonomy” is at once that which most clearly connects him with earlier inquirers like Anaximander, and also that which had the greatest influence on the subsequent development of philosophy. He observed, to begin with, that “most things human were two,” and by this he meant that man was made up of the hot and the cold, the moist and the dry, and the rest of the opposites. Disease was just the “monarchy” of any one of these—the same thing that Anaximander had called “injustice”—while health was the establishment in the body of a free government with equal laws. This was the leading doctrine or the Sicilian school of medicine, and we shall have to consider in the sequel its influence on the development of Pythagoreanism. Taken along with the theory of “pores,” it is of the greatest importance for later science.