As long as you are going to be thinking anyway, think big.

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

Many a man fails as an original thinker simply because his memory is too good.

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

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

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