I never view mistakes as failures. They are simply opportunities to find out what doesn't work.

I never did anything worth doing entirely by accident. . . Almost none of my inventions came about totally by accident. They were achieved by having trained myself to endure and tolerate hard work.

The trouble with most people is that they quit before they start.

Somewhere between the ages of eleven and fifteen, the average child begins to suffer from an atrophy, the paralysis of curiosity and the suspension of the power to observe. The trouble, I should judge, to lie with the schools.

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

Vision without execution is delusion.

Youth doesn't take advice.