This book, highly praised by A. Strindberg, was written from a natural philosophical perspective and represented a global "study" of the "masculine" and "feminine" principles. According to the author, the former is characterized by a high level of consciousness, creativity, and asceticism. The latter embodies a primitive model of consciousness, unproductive behavior, and sensuality. In addition to women, men – Jews and Negroes – also embody the "feminine" principle.