A failure teaches you that something can't be done-that way.

I never did anything by accident, nor did any of my inventions come by accident; they came by work.

When there's no experimenting there's no progress. Stop experimenting and you go backward. If anything goes wrong, experiment until you get to the very bottom of the trouble.

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.

When I have fully decided that a result is worth getting I go ahead of it and make trial after trial until it comes.

I have not failed. I've just found 10,000 ways that won't work.

There will one day spring from the brain of science a machine or force so fearful in its potentialities, so absolutely terrifying, that even man, the fighter, who will dare torture and death in order to inflict torture and death, will be appalled, and so abandon war forever.