I have always regarded that Constitution as the most remarkable work known to me in modern times to have been produced by the human intellect, at a single stroke (so to speak), in its application to political affairs.

What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.

I've always felt that a person's intelligence is directly reflected by the number of conflicting points of view he can entertain simultaneously on the same topic.

Appearances to the mind are of four kinds. Things either are what they appear to be; or they neither are, nor appear to be; or they are, and do not appear to be; or they are not, and yet appear to be. Rightly to aim in all these cases is the wise man’s task.

It doesn't matter how smart you are unless you stop and think.

The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.