Mortimer Adler

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

The tragedy of being both rational and animal seems to consist in having to choose between duty and desire rather than in making any particular choice

The ability to retain a child's view of the world with at the same time a mature understanding of what it means to retain it, is extremely rare - and a person who has these qualities is likely to be able to contribute something really important to our thinking.

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.

There are genuine mysteries in the world that mark the limits of human knowing and thinking. Wisdom is fortified, not destroyed, by understanding its limitations. Ignorance does not make a fool as surely as self-deception.