In this impressive synthesis of the research and investigation of a lifetime. Jean Piaget discusses the nature of intelligence and of knowledge in the light of contemporary findings in biology. He considers three kinds of knowledge; innate; knowledge gained through experience of the physical world; and logico-mathematical knowledge, independent of experience. The loss of Instinct in man has permitted a new cognitive evolution, so complete that logico-mathematical knowledge can be explained only by returning to the necessary biological framework. In an impressive analysis of the biological data of evolution, heredity, regulations, and embryological development on the one hand, psychogenetic information and current epistemological theory on the other, Piaget draws out correspondences between the structures of knowledge and those of life.