Life is a phenomenon sui generis, a primal fact in its own right, like energy. Cut flesh or wood how you like, hack at them in a baffled fury—you cannot find life itself, you can only see what it built out of the lifeless dust.

As the brain of man is the speck of dust in the universe that thinks, so the leaves—the fern and the needled pine and the latticed frond and the seaweed ribbon—perceive the light in a fundamental and constructive sense. … Their leaves see the light, as my eyes can never do. … They impound its stellar energy, and with that force they make life out of the elements.

The Grand Canyon is carven deep by the master hand; it is the gulf of silence, widened in the desert; it is all time inscribing the naked rock; it is the book of earth.

All the great naturalists have been habitual walkers, for no laboratory, no book, car, train or plane takes the place of honest footwork for this calling, be it amateur's or professional's.

Life is a phenomenon sui generis, a primal fact in its own right, like energy. Cut flesh or wood how you like, hack at them in a baffled fury—you cannot find life itself, you can only see what it built out of the lifeless dust.

Time is not money; time is an opportunity to live before you die. So a man who walks, and lives and sees and thinks as he walks, has lengthened his life.

I have often started off on a walk in the state called mad-mad in the sense of sore-headed, or mad with tedium or confusion; I have set forth dull, null and even thoroughly discouraged. But I never came back in such a frame of mind, and I never met a human being whose humor was not the better for a walk.