The stomach is the only part of man which can be fully satisfied. The yearning of man's brain for new knowledge and experience and for more pleasant and comfortable surroundings never can be completely met. It is an appetite which cannot be appeased.

Restlessness is discontent and discontent is the first necessity of progress. Show me a thoroughly satisfied man and I will show you a failure.

It is apparent to me that the possibilities of the aeroplane, which two or three years ago were thought to hold the solution to the [flying machine] problem, have been exhausted, and that we must turn elsewhere.

I have been at work for some time building an apparatus to see if it is possible for personalities which have left this earth to communicate with us.

To have a great idea, have a lot of them.

Being busy does not always mean real work. The object of all work is production or accomplishment and to either of these ends there must be forethought, system, planning, intelligence, and honest purpose, as well as perspiration. Seeming to do is not doing.

The three things that are most essential to achievement are common sense, hard work and stick-to-it-iv-ness.