The best protection against propaganda of any sort is the recognition of it for what it is. Only hidden and undetected oratory is really insidious. What reaches the heart without going through the mind is likely to bounce back and put the mind out of business. Propaganda taken in that way is like a drug you do not know you are swallowing. The effect is mysterious; you do not know afterwards why you feel or think the way you do.

All genuine learning is active, not passive. It involves the use of the mind, not just the memory. It is a process of discovery, in which the student is the main agent, not the teacher.

I find the selectivity of erotic love - the choice of this man or this woman - much more intelligible if liking the person is the origin of sexual interest, rather than the other way.

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

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 complexities of adult life get in the way of the truth. The great philosophers have always been able to clear away the complexities and see simple distinctions - simple once they are stated, vastly difficult before. If we are to follow them we too must be childishly simple in our questions - and maturely wise in our replies.

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.