The difference between intelligence and education is this: intelligence will make you a good living.

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.

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.

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

The first method of estimating the intelligence of a ruler is to look at the men he has around him.

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.

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

In walking, the will and the muscles are so accustomed to working together and performing their task with so little expenditure of force that the intellect is left comparatively free.