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.

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

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

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 main source of psychopathic diseases is the fundamental instinct of fear with its manifestations, the feeling of anxiety, anguish, and worry.

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