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.

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

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

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

All that exists, exists in some amount and can be measured.

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.