Our greatest weakness lies in giving up. The most certain way to succeed is to try just one more time

To invent, you need a good imagination and a pile of junk

I never did anything worth doing by accident, nor did any of my inventions come by accident

Just because something doesn't do what you planned it to do doesn't mean it's useless

Opportunity is missed by most people because it is dressed in overalls and looks like work

There is no substitute for hard work