The whole of science is nothing more than a refinement of everyday thinking.

Any man who reads too much and uses his own brain too little falls into lazy habits of thinking.

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.

There is nothing either good or bad but thinking makes it so.

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.