My mind is incapable of conceiving such a thing as a soul. I may be in error, and man may have a soul; but I simply do not believe it.

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.

Negative results are just what I want. They’re just as valuable to me as positive results. I can never find the thing that does the job best until I find the ones that don’t.

A genius is a talented person who does his homework.

Nothing that's good works by itself, you've got to make the damn thing work.

To those searching for truth -- not the truth of dogma and darkness but the truth brought by reason, search, examination, and inquiry, discipline is required. For faith, as well intentioned as it may be, must be built on facts, not fiction -- faith in fiction is a damnable false hope.

IF PARENTS PASS ENTHUSIASM ALONG TO THEIR CHILDREN, THEY WILL LEAVE THEM AN ESTATE OF INCALCULABLE VALUE