"Moreover, that the senses are drops from them; and that the reasoning sense is immortal, but the others are mortal. And that the soul is nourished by the blood; and that reasons are the winds of the soul. That it is invisible, and so are its reasons, since the aether itself is invisible. That the links of the soul are the veins and the arteries and the nerves. But that when it is vigorous, and is by itself in a quiescent state, then its links are words and actions. That when it is cast forth upon the earth it wanders about, resembling the body. Moreover, that Mercury is the steward of the souls, and that on this account he has the name of Conductor, and Commercial, and Infernal, since it is he who conducts the souls from their bodies, and from earth and sea; and that he conducts the pure souls to the highest region, and that he does not allow the impure ones to approach them, nor to come near one another, but commits them to be bound in indissoluble fetters by the Furies. The Pythagoreans also assert that the whole air is full of souls, and that these are those which are accounted daemons and heroes. Also, that it is by them that dreams are sent among men, and also the tokens of disease and health; these last, too, being sent not only to men, but to sheep also, and other cattle. Also that it is they who are concerned with purifications and expiations and all kinds of divination and oracular predictions, and things of that kind."(5) A brief consideration of this summary of the doctrines of Pythagoras will show that it at least outlines a most extraordinary variety of scientific ideas. (1) There is suggested a theory of monads and the conception of the development from simple to more complex bodies, passing through the stages of lines, plain figures, and solids to sensible bodies. (2) The doctrine of the four elements--fire, water, earth, and air--as the basis of all organisms is put forward. (3) The idea, not merely of the sphericity of the earth, but an explicit conception of the antipodes, is expressed. (4) A conception of the sanitary influence of the air is clearly expressed. (5) An idea of the problems of generation and heredity is shown, together with a distinct disavowal of the doctrine of spontaneous generation--a doctrine which, it may be added, remained in vogue, nevertheless, for some twenty-four hundred years after the time of Pythagoras. (6) A remarkable analysis of mind is made, and a distinction between animal minds and the human mind is based on this analysis. The physiological doctrine that the heart is the organ of one department of mind is offset by the clear statement that the remaining factors of mind reside in the brain. This early recognition of brain as the organ of mind must not be forgotten in our later studies. It should be recalled, however, that a Crotonian physician, Alemaean, a younger contemporary of Pythagoras, is also credited with the same theory. (7) A knowledge of anatomy is at least