the male, is exclusively formative; and the other, that contributed by the female, exclusively material. The prevalent opinion was evidently, what we know now to be true, that each parent has both a formative and a material share in the composition of the embryo. Again, Aristotle, strangely enough, regards the generative element in both sexes as an unappropriated portion of the animal’s nutriment, the last and most refined product of digestion, and therefore not a portion of the parental system at all; while other biologists, anticipating Mr. Darwin’s theory of pangenesis in a very wonderful manner, taught that the semen is a conflux of molecules derived from every part of the body, and thus strove to account for the hereditary transmission of individual peculiarities to offspring.[202] All these, however, are mere questions of detail. It is on a subject of the profoundest philosophical importance that Aristotle differs most consciously, most radically, and most fatally from his predecessors. They were evolutionists, and he was a stationarist. They were mechanicists, and he was a teleologist. They were uniformitarians, and he was a dualist. It is true that, as we mentioned at the beginning of this chapter, Mr. Edwin Wallace makes him ‘recognise the genesis of things by evolution and development,’ but the meaning of this phrase requires to be cleared up. In one sense it is, of course, almost an identical proposition. The genesis of things must be by genesis of some kind or other. The great question is, what things have been evolved, and how have they been evolved? Modern science tells us, that not only have all particular aggregates of matter and motion now existing come into being within a finite period of time, but also that the specific types under which we arrange those aggregates have equally been generated; and that their characteristics, whether structural or functional, can only be understood by tracing out their origin and history. And it further teaches us that the properties of every aggregate result from the properties of its ultimate elements, which, within the limits of our experience, remain absolutely unchanged. Now, Aristotle taught very nearly the contrary of all this. He believed that the cosmos, as we now know it, had existed, and would continue to exist, unchanged through all eternity. The sun, moon, planets, and stars, together with the orbs containing them, are composed of an absolutely ungenerable, incorruptible substance. The earth, a cold, heavy, solid sphere, though liable to superficial changes, has always occupied its present position in the centre of the universe. The specific forms of animal life—except a few which are produced spontaneously—have, in like manner, been preserved unaltered through an infinite series of generations. Man shares the common lot. There is no continuous progress of civilisation. Every invention and discovery has been made and lost an infinite number of times. Our philosopher