Such views certainly flew in the face of the universal modern conviction that the present mode of knowledge, with whose help so much insight into the natural world has been won, is the only one possible, given once for all to man in a form never to be changed. But is there any need, I asked myself, to cling to this purely static notion of man's capacity for gaining knowledge? Among the greatest achievements of modern science, does not the conception of evolution take a foremost place? And does not this teach us that the condition of a living organism at any time is the result of the one preceding it, and that the transition implies a corresponding functional enhancement? But if we have once recognized this as an established truth, why should we apply it to organisms at every stage of development except the .highest, namely the human, where the organic form reveals and serves the self-conscious spirit?