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.

Dogs get lost hundreds of times and no one ever notices it or sends an account of it to a scientific magazine.

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

It will of course, be understood that directly or indirectly, soon or late, every advance in the sciences of human nature will contribute to our success in controlling human nature and changing it to the advantage of the common wheel.

He who learns and runs away, lives to learn another day.

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 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.