All I have to do is think and not be influenced by other.

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.

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 best thinking has been done in solitude. The worst has been done in turmoil.