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.

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

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

Mental synthesis of psychic content in the unity of a moment-consciousness is a fundamental principle of psychology.

Psychology must postulate uniformity of interrelation of physical, physiological, and psychic processes.

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

The man of genius whether as artist or thinker requires a mass of accidental variations to select from and a rigidly selective process of attention.