We cannot walk through life on mountain peaks.

Nature exists for man no more than she does for monkeys, and is as regardless of his life or pleasure or success as she is of the fleas. Her waves will drown him, her fire burn him, and her earth devour him, her storms and lightning smite him, as if he were only a dog.

The art of nature is all in the direction of concealment.

The simplicity of winter has a deep moral. The return of Nature, after such a career of splendor and prodigality, to habits so simple and austere, is not lost either upon the head or the heart. It is the philosopher coming back from the banquet and the wine to a cup of water and a crust of bread.

I seldom go into a natural history museum without feeling as if I were attending a funeral.

We can outrun the wind and the storm, but we cannot outrun the demon of hurry.

There are nine countries in the world that have nuclear weapons. There are about 27,000 nuclear weapons total on the planet. The countries that have nuclear weapons deploy them ready for use and have doctrines saying that they would use them in certain circumstances.