Nowhere more truly than in his mental capacities is man a part of nature.

Amongst the minds of animals that of man leads, not as a demigod from another planet, but as a king from the same race.

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

Psychology helps to measure the probability that an aim is attainable.

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.

This growth in the number, speed of formation, permanence, delicacy and complexity of associations possible for an animal reaches its acme in the case of man.