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

For origin and development of human faculty we must look to these processes of association in lower animals.

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.

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

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

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

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