One can only learn his powers of action by action, and his powers of thought by thinking

Mounting toward the upland again, I pause reverently, as the hush and stillness of twilight come upon the woods. It is the sweetest, ripest hour of the day. And as the hermit's evening hymn goes up from the deep solitude below me, I experience that serene exaltation of sentiment of which music, literature, and religion are but the faint types and symbols.

Natural history is a matter of observation; it is a harvest which you gather when and where you find it growing. Birds and squirrels and flowers are not always in season, but philosophy we have always with us. It is a crop which we can grow and reap at all times and in all places and it has its own value and brings its own satisfaction.

Man is, and always has been, a maker of gods. It has been the most serious and significant occupation of his sojourn in the world.

I am in love with this world. It has been my home. It has been my point of outlook into the universe. I have never bruised myself against it nor tried to use it ignobly.

A man can fail many times, but he isn't a failure until he begins to blame somebody else.

The fuel in the earth will be exhausted in a thousand or more years, and its mineral wealth, but man will find substitutes for these in the winds, the waves, the sun's heat, and so forth.