To illustrate this fact, I have drawn up a curve of the sexual life of woman, making use of the statistical data available in central Europe regarding the age at which menstruation first appears, the age at which maidens marry, the age at which the largest number of women give birth to a child, and the age at which menstruation ceases; and reducing the figures to averages. * denotes the fifteenth year of life, as the average age at the menarche; ** denotes the twenty-second year of life as the average age at marriage; *** denotes the thirty-second year of life, in which woman exhibits her maximum fecundity; **** denotes the forty-sixth year of life as the average age at the menopause. (FIG. 1.) [Illustration: FIG. 1.—Curve of the sexual life of woman from the tenth to the sixtieth year of life. ] Not in this respect alone, however, is the sexual life of woman of paramount importance; it is, in addition, the mainspring of the well-being and progress of the family, of the nation, of the entire human race. In the evolution of man from the primitive state in which he existed merely for the performance of vegetative functions up to the highest stage of contemporary culture, in the history of all races and of all times, the sexual life has been a most potent determining factor. With that life, religion, philosophy, ethics, natural science, and hygiene, have been most intimately related; for that life, they have furnished precepts and laws. The history of the sexual life is identical with the history of human culture.