Human institutions depend for their existence and stability on the impulse of self-preservation and its close associate, - the fear instinct.

The tendency of life is not the preservation of the species, but solely the preservation of each individual organism, as long as it is in existence at all, and is able to carry on its life processes.

The principle of recognition of evil under all its guises is at the basis of the true education of man.

Not purpose but chance is at the heart of mental life.

The general tendency of evolution is from structure to function, from bondage to freedom of the individual elements.

Self-preservation is the central aim of all life-activities.

Social laughter is momentary, soon burns itself out and passes away like the fire and smokes of straw, but genius shakes the very skies with its lasting, inextinguishable laughter.