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

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.

All thinking begins with wondering.

Even people who aren't geniuses can outthink the rest of mankind if they develop certain thinking habits.