Theory must mediate between all previous truths and certain new experiences

Pretend what we may, the whole man within us is at work when we form our philosophical opinions. Intellect, will, taste, and passion co-operate just as they do in practical affairs; and lucky it is if the passion be not something as petty as a love of personal conquest over the philosopher across the way.

Truth is what will be steadily borne out by subsequent experience

You must bring out of each word its practical cash-value, set it at work within the stream of your experience.

The first lecture in psychology that I ever heard was the first I ever gave.

The entire routine of our memorized acquisitions, for example, is a consequence of nothing but the Law of Contiguity. The words of a poem, the formulas of trigonometry, the facts of history, the properties of material things, are all known to us as definite systems or groups of objects which cohere in an order fixed by innumerable iterations, and of which any one part reminds us of the others.

Genius... means little more than the faculty of perceiving in an unhabitual way.