There is a strange fact about the human mind, a fact that differentiates the mind sharply from the body. The body is limited in ways that the mind is not. One sign of this is that the body does not continue indefinitely to grow in strength and develop in skill and grace. By the time most people are thirty years old, their bodies are as good as they will ever be; in fact, many persons' bodies have begun to deteriorate by that time. But there is no limit to the amount of growth and development that the mind can sustain. The mind does not stop growing at any particular age.

The telephone book is full of facts, but it doesn't contain a single idea.

Habits are formed by the repetition of particular acts. They are strengthened by an increase in the number of repeated acts. Habits are also weakened or broken, and contrary habits are formed by the repetition of contrary acts.

The complexities of adult life get in the way of the truth.

We are selfish when we are exclusively or predominantly concerned with the good for ourselves. We are altruistic when we are exclusively or predominantly concerned with the good of others.

One of the embarrassing problems for the early nineteenth-century champions of the Christian faith was that not one of the first six Presidents of the United States was an orthodox Christian.

Philosophy is everybody's business.