Reproduction is so primitive and fundamental a function of vital organisms that the mechanism by which it is assured is highly complex and not yet clearly understood. It is not necessarily connected with sex, nor is sex necessarily connected with reproduction.

Where there is most labour there is not always most life.

...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 more rapidly a civilization progresses, the sooner it dies for another to rise in its place.

Heroes exterminate each other for the benefit of people who are not heroes.

The place where optimism most flourishes is the lunatic asylum.

Mankind is becoming a single unit, and that for a unit to fight against itself is suicide.