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.

Washington is no place in which to carry out inventions

I have heard articulate speech produced by sunlight I have heard a ray of the sun laugh and cough and sing! … I have been able to hear a shadow, and I have even perceived by ear the passage of a cloud across the sun's disk.

One day every major city in America will have a telephone.

Leave the beaten track behind occasionally and dive into the woods.

Watson, ... if I can get a mechanism which will make a current of electricity vary in its intensity, as the air varies in density when a sound is passing through it, I can telegraph any sound, even the sound of speech.

When one door closes, another opens; but we often look so long and so regretfully upon the closed door that we do not see the one which has opened for us.