If we understand by metaphysics the science of the ultimate ground of things, springing from the rational demand for causes, it can only be regarded, from the physiological point of view, as a higher and late-developed function of the phronema. It could only arise with the complete development of the brain in civilized man. It is completely lacking among savages, whose organ of thought rises very little above that of the most intelligent animals. The laws of the psychic life of the savage have been closely studied by modern ethnology. It teaches us that the higher reason is not found in savages, and that their power of abstract thought and of forming concepts is at a very low level. Thus, for instance, the Veddahs, who live in the forests of Ceylon, have not the general idea of trees, though they know and give names to individual trees. Many savages cannot count up to five; they never reflect on the ground of their existence or think of the past or future. Hence it is a great error for Schopenhauer and other philosophers to define man as a "metaphysical animal," and to seek a profound distinction between man and the animal in the need for a metaphysic. This craving has only been awakened and developed by the progress of civilization. But even in civilized communities it (like consciousness) is not found in early youth, and only gradually emerges. The child has to learn to speak and think. In harmony with our biogenetic law, the child reproduces in the various stages of its mental development the whole of the gradations which lead from the savage to the barbarian, and from the barbarian to the half-civilized, and on to the fully educated man. If this historical development of the higher human faculties had always been properly appreciated, and psychology had been faithful to the comparative and genetic methods, many of the errors of the current metaphysical systems would have been avoided. Kant would not then have produced his theory of _a priori_ knowledge, but would have seen that all that now seems to be _a priori_ in civilized man was originally acquired by _a posteriori_ experiences in the long evolution of civilization and science. Here we have the root of the errors which are distinctive of dualism and the prevailing metaphysical transcendentalism.