I did not fail two thousand times. I merely found two thousand ways not to make a lightbulb.

Success depends on how many experiments you can fit into 24 hours

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

X-rays ... I am afraid of them. I stopped experimenting with them two years ago, when I came near to losing my eyesight and Dally, my assistant practically lost the use of both of his arms.

I've never made a mistake. I've only learned from experience.

If the Nation can issue a dollar bond it can issue a dollar bill. The element that makes the bond good makes the bill good also. The difference between the bond and the bill is that the bond lets the money broker collect twice the amount of the bond and an additional 20%. Whereas the currency, the honest sort provided by the Constitution pays nobody but those who contribute in some useful way. It is absurd to say our Country can issue bonds and cannot issue currency. Both are promises to pay, but one fattens the usurer and the other helps the People.

Discontent is the first necessity of progress.