Three elements go to make up an idea. The first is its intrinsic quality as a feeling. The second is the energy with which it affects other ideas, an energy which is infinite in the here-and-nowness of immediate sensation, finite and relative in the recency of the past. The third element is the tendency of an idea to bring along other ideas with it.

The essence of belief is the establishment of a habit; and different beliefs are distinguished by the different modes of action to which they give rise.

It is a common observation that a science first begins to be exact when it is quantitatively treated. What are called the exact sciences are no others than the mathematical ones.

It is a common observation that those who dwell continually upon their expectations are apt to become oblivious to the requirements of their actual situation.

One will meet, for example, the virtual assumption that what is relative to thought cannot be real. But why not, exactly? Red is relative to sight, but the fact that this or that is in that relation to vision that we call being red is not itself relative to sight; it is a real fact.

All the progress we have made in philosophy ... is the result of that methodical skepticism which is the element of human freedom.

We, one and all of us, have an instinct to pray; and this fact constitutes an invitation from God to pray.