Good fortune is what happens when opportunity meets with planning.

The reason a lot of people do not recognize opportunity is because it usually goes around wearing overalls looking like hard work.

I consider Paine our greatest political thinker. As we have not advanced, and perhaps never shall advance, beyond the Declaration and Constitution, so Paine has had no successors who extended his principles.

I am afraid of radium and polonium ... I don't want to monkey with them.

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

I never perfected an invention that I did not think about in terms of the service it might give others... I find out what the world needs, then I proceed to invent.

I never pick up an item without thinking of how I might improve it. I never perfected an invention that I did not think about in terms of the service it might give others. I want to save and advance human life, not destroy it. I am proud of the fact that I never invented weapons to kill. The dove is my emblem.