The distinction of sex is a first principle: An animal is not male or female in virtue of an isolated part or an isolated faculty: when that which distinguishes male and female suffers change many other changes accompany it, as would be the case if a first principle is changed.[11] The treatise is concerned chiefly with the phenomena of reproduction: For the business of most animals is, you may say, nothing else than to produce young, as the business of a plant is to produce seed and fruit.[12] Sex-characteristics accordingly are described mainly in accordance with their reproductive functions. As regards the origin of sex and the causes of male and female, Aristotle is a curious mixture of prejudice and insight. He begins thus: To suppose that heat and cold are the causes of male and female, or that the different sexes come from the right and left, is not altogether unreasonable in itself, for the right of the body is hotter than the left. With him it is an unquestioning belief that the right is, in nature, superior to the left, the upper to the lower, the front to the back; and nature, when no more important purpose stands in the way, places the more honourable part in the more honourable position. So it is that the heart, which is the nobler organ, is in the upper part of the body, while the stomach is in the lower. As he is equally sure that the male is superior to the female, the male elements in reproduction will come from the right or noble part of the body. But the part taken by the male and female elements in the process of generation is, according to Aristotle, absolutely different. The child is not formed from a mixture of both, but the female contributes the material, the male is the active agent. The analogy used is that of a bed: the female is the wood, the male the carpenter, who, from the wood, makes the bed. The female is passive, the male is active: It is through a certain incapacity that the female is female: females are weaker and colder in nature than males, and we must look upon the female character as being a sort of natural deficiency.[13] Women, in Aristotle’s view, are rather plants than animals; for the animal differs from the plant, chiefly in having sense-perception. If the sensitive soul is not present, the body is no better than a corpse, and this sensitive soul is supplied only by the male. The female provides the material, the male fashions it; the body is from the female, the soul from the male, who can stand outside the body just as the artist stands outside his creation. It certainly seems that female children progress more quickly than male, but that is merely a proof of their inferiority; for all inferior things come sooner to their perfection or end, and as this is true of works of art so it is true of what is formed by nature.