What is man but a mass of thawing clay?

You can hardly convince a man of an error in a lifetime, but must content yourself with the reflection that the progress of science is slow. If he is not convinced, his grandchildren may be.

I saw deep in the eyes of the animals the human soul look out upon me. I saw where it was born deep down under feathers and fur, or condemned for a while to roam four-footed among the brambles,I caught the clinging mute glance of the prisoner and swore that I would be faithful.

What means the fact--which is so common, so universal--that some soul that has lost all hope for itself can inspire in another listening soul an infinite confidence in it, even while it is expressing its despair?

Nature is slow, but sure; she works no faster than need be; she is the tortoise that wins the race by her perseverance.

I only desire sincere relations with the worthiest of my acquaintance, that they may give me an opportunity once in a year to speak the truth.

There is a chasm between knowledge and ignorance which the arches of science can never span.