Perseverance must have some practical end, or it does not avail the…

There cannot be mental atrophy in any person who continues to observe, to remember what he observes, and to seek answers for his unceasing hows and whys about things.

The inventor...looks upon the world and is not contented with things as they are. He wants to improve whatever he sees, he wants to benefit the world; he is haunted by an idea. The spirit of invention possesses him, seeking materialization.

Mr. Watson — Come here — I want to see you.

The final result of our researches has widened the class of substances sensitive to light vibrations, until we can propound the fact of such sensitiveness being a general property of all matter.

Neither the Army nor the Navy is of any protection, or very little protection, against aerial raids.

I begin my work at about nine or ten o'clock in the evening and continue until four or five in the morning. Night is a more quiet time to work. It aids thought.