Anything that won't sell, I don't want to invent. Its sale is proof of utility, and utility is success.

I try not to invent things that people don't need.

The greatest invention in the world is the mind of a child.

I start where the last man left off.

I owe my success to the fact that I never had a clock in my workroom.

I find out what the world needs. Then I go ahead and try to invent it.