We will make electricity so cheap that only the rich will burn candles.

If we did the things we are capable of, we would astound ourselves.

Time is really the only capital that any human being has, and the only thing he can't afford to lose.

The best thinking has been done in solitude.

TO do much clear thinking a man must arrange for regular periods of solitude when he can concentrate and indulge his imagination without distraction.

Discontent is the first necessity of progress.