To do much clear thinking a person must arrange for regular periods of solitude when they can concentrate and indulge the imagination without distraction.

There is no limit to which a man will not go to avoid thinking.

The man who doesn't make up his mind to cultivate the habit of thinking misses the greatest pleasure in life.

The trouble with most people is that they quit before they start.

Whatever you think, that you will be. If you think yourselves weak, weak you will be; if you think yourselves strong, strong you will be.

Debates conceal rather than reveal the truth. Truth is revealed in solitude.