Opinion is ultimately determined by the feelings, and not by intellect.

Intelligent people tend to have less friends than the average person. The smarter you are, the more selective you become.

It is not reason which is the guide of life, but custom.

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

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.

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.

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.

To criticize is to appreciate, to appropriate, to take intellectual possession, to establish in fine a relation with the criticized thing and to make it one's own.

Men have called me mad; but the question is not yet settled, whether madness is or is not the loftiest intelligence.