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

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

Human beings are accustomed to think of intellect as the power of having and controlling ideas and of ability to learn as synonymous with ability to have ideas. But learning by having ideas is really one of the rare and isolated events in 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.

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

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.

When, instead of merely associating some act with some situation in the animal way, we think the situation out, we have a set of particular feelings of its elements.