The conflict of forces and the struggle of opposing wills are of the essence of our universe and alone hold it together.

A man must not swallow more beliefs than he can digest.

If men and women are to understand each other, to enter into each other's nature with mutual sympathy, and to become capable of genuine comradeship, the foundation must be laid in youth.

The omnipresent process of sex, as it is woven into the whole texture of our man's or woman's body, is the pattern of all the process of our life.

The sexual regions constitute a particularly vulnerable spot, and remain so even in man, and the need for their protection which thus exists conflicts with the prominent display required for sexual allurement. This end is far more effectively attained, with greater advantage and less disadvantage, by concentrating the chief ensigns of sexual attractiveness on the upper and more conspicuous parts of the body. This method is well-nigh universal among animals as well as in man.

...aesthetic values are changed under the influence of sexual emotion; from the lover's point of view many things are beautiful which are unbeautiful from the point of view of him who is not a lover, and the greater the degree to which the lover is swayed by his passion the greater the extent to which his normal aesthetic standard is liable to be modified.

The prevalence of suicide, without doubt, is a test of height in civilization; it means that the population is winding up its nervous and intellectual system to the utmost point of tension and that sometimes it snaps.