Tact is the art of making a point without making an enemy.

Errors are not in the art but in the artificers.

I was like a boy playing on the sea-shore, and diverting myself now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.

If I have done the public any service, it is due to my patient thought.

To me there has never been a higher source of earthly honor or distinction than that connected with advances in science.