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 teacher's role in discussion is to keep it going along fruitful lines - be moderating, guiding, correcting and arguing like one more students.

To agree without understanding is inane. To disagree without understanding is impudent.

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.

Ultimately there can be no disagreement between history, science, philosophy, and theology. Where there is disagreement, there is either ignorance or error.

Men value things in three ways: as useful, as pleasant or sources of pleasure, and as excellent, or as intrinsically admirable or honorable.

The truly great books are the few books that are over everybody's head all of the time.