When one is friend on himself, also is friend of everybody.

A single lifetime, even though entirely devoted to the sky, would not be enough for the study of so vast a subject. A time will come when our descendants will be amazed that we did not know things that are so plain to them.

Great is he who enjoys his earthenware as if it were plate, and not less great is the man to whom all his plate is no more that earthenware.

Truth never perishes.

Certain laws have not been written, but they are more fixed than all the written laws.

One of the most beautiful qualities of true friendship is to understand and to be understood.

The profit on a good action is to have done it.