Nature does nothing in vain.

Gray hairs are signs of wisdom if you hold your tongue, speak and they are but hairs, as in the young.

When you're young, you look at television and think, there's a conspiracy. The networks have conspired to dumb us down. But when you get a little older, you realize that's not true. The networks are in business to give people exactly what they want.

There could be no fairer destiny for any physical theory than that it should point the way to a more comprehensive theory in which it lives on as a limiting case. 

It is better to travel well than to arrive.

Russia is a riddle wrapped in a mystery inside an enigma. 

However many holy words you read, however many you speak, what good will they do you if you do not act on upon them?

Sure I am of this, that you have only to endure to conquer.

Constant development is the law of life, and a man who always tries to maintain his dogmas in order to appear consistent drives himself into a false position.

Love is not a mere impulse, it must contain truth, which is law.

We forge the chains we wear in life.

The miracle is not that we do this work, but that we are happy to do it.