experience, has the changeless consistency once attributed exclusively to the stellar spheres. When Aristotle passes from the whole cosmos to the philosophy of life, his method of systematic division is less distinctly illustrated, but still it may be traced. The fundamental separation is between body and soul. The latter has a wider meaning than what we associate with it at present. It covers the psychic functions and the whole life of the organism, which, again, is not what we mean by life. For life with us is both individual and collective; it resides in each speck of protoplasm, and also in the consensus of the whole organism. With Aristotle it is more exclusively a central principle, the final cause of the organism, the power which holds it together, and by which it was originally shaped. Biology begins by determining the idea of the whole, and then considers the means by which it is realised. The psychic functions are arranged according to a system of teleological subordination. The lower precedes the higher in time, but is logically necessitated by it. Thus nutrition, or the vegetative life in general, must be studied in close connexion with sensation and impulse, or animal life; and this, again, with thought or pure reasoning. On the other hand, anatomy and physiology are considered from a purely chemical and mechanical point of view. A vital purpose is, indeed, assigned to every organ, but with no more reference to its specifically vital properties than if it formed part of a steam engine. Here, as always with Aristotle, the idea of moderation determines the point of view whence the inferior or material system is to be studied. Organic tissue is made up of the four elemental principles—hot, cold, wet, and dry—mixed together in proper proportions; and the object of organic function is to maintain them in due equilibrium, an end effected by the regulating power of the soul, which, accordingly, has its seat in the heart or centre of the body. It has been already shown how, in endeavouring to work out this chimerical theory, Aristotle went much further astray from the truth than sundry other Greek physiologists less biassed by the requirements of a symmetrical method.