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

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

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

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.

The intellectual evolution of the race consists in an increase in the number, delicacy, complexity, permanence and speed of formation of such associations.

On the whole, the psychological work of the last quarter of the nineteenth century emphasized the study of consciousness to the neglect of the total life of intellect and character

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.