Sex enters into all these subjects and should not be artificially excluded from them in the education of either boys or girls.

The text-books from which the sexual system is entirely omitted ought no longer to be tolerated.

The nature and secretion of the testicles, the meaning of the ovaries and of menstruation, as well as the significance of metabolism and the urinary excretion, should be clear in their main lines to all boys and girls who have reached the age of puberty.
At puberty there arises a new and powerful reason why boys and girls should receive definite instruction in matters of sex.

Before that age it is possible for the foolish parent to imagine that a child may be preserved in ignorant innocence.[25] At puberty that belief is obviously no longer possible.

The efflorescence of puberty with the development of the sexual organs, the appearance of hair in unfamiliar places, the general related organic changes, the spontaneous and perhaps alarming occurrence in boys of seminal emissions, and in girls of menstruation, the unaccustomed and sometimes acute recognition of sexual desire accompanied by new sensations in the sexual organs and leading perhaps to masturbation; all these arouse, as we cannot fail to realize, a new anxiety in the boy's or girl's mind, and a new curiosity, all the more acute in many cases because it is carefully concealed as too private, and even too shameful, to speak of to anyone.