We go on dating from Cold Fridays and Great Snows; but a little colder Friday, or greater snow would put a period to man's existence on the globe.

We need the tonic of wildness.

Whatever is, and is not ashamed to be, is good.

Books of natural history make the most cheerful winter reading. I read in Audubon with a thrill of delight, when the snow covers the ground, of the magnolia, and the Florida keys, and their warm sea breezes; of the fence-rail, and the cotton-tree, and the migrations of the rice-bird; of the breaking up of winter in Labrador, and the melting of the snow on the forks of the Missouri; and owe an accession of health to these reminiscences of luxuriant nature.

There is more of good nature than of good sense at the bottom of most marriages.

He is not a true man of science who does not bring some sympathy to his studies, and expect to learn something by behavior as well as by application. It is childish to rest in the discovery of mere coincidences, or of partial and extraneous laws. The study of geometry is a petty and idle exercise of the mind, if it is applied to no larger system than the starry one. Mathematics should be mixed not only with physics but with ethics; that is mixed mathematics. The fact which interests us most is the life of the naturalist. The purest science is still biographical.

I suspect that, if you should go to the end of the world, you would find somebody there going farther, as if just starting for home at sundown, and having a last word before he drove off.