Just as the science and art of agriculture depend upon chemistry and botany, so the art of education depends upon physiology and psychology.

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 dog, on the other hand, has few or no ideas because his brain acts in coarse fashion and because there are few connections with each single process.

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.

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.

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

The restriction of studies of human intellect and character to studies of conscious states was not without influence on a scientific studies of animal psychology.