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

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.

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

The most important thing is transforming our minds, for a new way of thinking, a new outlook: we should strive to develop a new inner world.

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