The money one gets for selling one's soul is always spent in deadening one's conscience, so the net gain at the end of a lifetime is no greater than if the diabolic bargain had not been struck.

I never did anything worth doing by accident, nor did any of my inventions come indirectly through accident, except the phonograph. No, when I have, fully decided that a result is worth getting, I go about it, and make trial after trial, until it comes.

Five percent of the people think; ten percent of the people think they think; and the other eighty-five percent would rather die than think.

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.

I start where the last man left off. What the mind of man can conceive and believe, the mind of a man can achieve.

The greatest discoveries will be along spiritual lines. This is the field where miracles are going to happen. Spiritual power is the greatest underdeveloped power and has the greatest future.

Failure is the most effective technique to optimize strategic planning, implementation and processes.