Keep silence for the most part, and speak only when you must, and then briefly.

The world is a book, and those who do not travel read only a page.

Eternal vigilance is the price of knowledge.

To care for anyone else enough to make their problems one's own is the beginning of ethical development.

Nature is painting for us, day after day, pictures of infinite beauty if only we have the eyes to see them.

The land does not belong to us; we belong to the land.

Either you decide to stay in the shallow end of the pool or you go out in the ocean.