The three things that are most essential to achievement are common sense, hard work and stick-to-it-iv-ness... Unfortunately, many of life's failures are experienced by people who did not realize how close they were to success when they gave up. I have far more respect for the person with a single idea who gets there than for the person with a thousand ideas who does nothing.

I have a peculiar theory about radium, and I believe it is the correct one. I believe that there is some mysterious ray pervading the universe that is fluorescing to it. In other words, that all its energy is not self-constructed but that there is a mysterious something in the atmosphere that scientists have not found that is drawing out those infinitesimal atoms and distributing them forcefully and indestructibly.

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

Waste is worse than loss. The time is coming when every person who lays claim to ability will keep the question of waste before him constantly. The scope of thrift is limitless.

Be brave as your fathers before you. Have faith and go forward.

Maturity is often more absurd than youth and very frequently is most unjust to youth.

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.