Whatever exists at all exists in some amount. To know it thoroughly involves knowing its quantity as well as its quality.

Some statements concern the conscious states of the animal, what he is to himself as an inner life; others concern his original and acquired ways of response, his behavior, what he is an outside observer

The real difference between a man's scientific judgments about himself and the judgment of others about him is he has added sources of knowledge.

The un-conscious distortion of the facts is almost harmless compared to the unconscious neglect of an animal's mental life until it verges on the unusual and marvelous.

To the intelligent man with an interest in human nature it must often appear strange that so much of the energy of the scientific world has been spent on the study of the body and so little on the study of the mind.

All that exists, exists in some amount and can be measured.

Psychology is the science of the intellects, characters and behavior of animals including man.