The book by the Swiss psychologist Jean Piaget presents an exposition of the essence of the theoretical concept of the development of intelligence, which is the basis, the core of mental development, the construction of which he carried out in the 30-40s. He considered the principles of this concept to be key to understanding the evolution of thinking in different historical eras and for various fields of knowledge; He developed, based on this position, a special direction of research, which he later called genetic epistemology.