Nor need our more sentimental economists fear the too wide spread of the formalities of a mechanical agriculture. The presence of a wise population implies the search for felicity as well as for food; nor can any population reach its maximum but through that wisdom which "rejoices" in the habitable parts of the earth. The desert has its appointed place and work; the eternal engine, whose beam is the earth's axle, whose beat is its year, and whose breath is its ocean, will still divide imperiously to their desert kingdoms, bound with unfurrowable rock, and swept by unarrested sand, their powers of frost and fire: but the zones and lands between, habitable, will be loveliest in habitation. The desire of the heart is also the light of the eyes. No scene is continually and untiringly loved, but one rich by joyful human labour; smooth in field; fair in garden; full in orchard; trim, sweet, and frequent in homestead; ringing with voices of vivid existence. No air is sweet that is silent; it is only sweet when full of low currents of under sound--triplets of birds, and murmur and chirp of insects, and deep-toned words of men, and wayward trebles of childhood. As the art of life is learned, it will be found at last that all lovely things are also necessary:--the wild flower by the wayside, as well as the tended corn; and the wild birds and creatures of the forest, as well as the tended cattle; because man doth not live by bread only, but also by the desert manna; by every wondrous word and unknowable work of God. Happy, in that he knew them not, nor did his fathers know; and that round about him reaches yet into the infinite, the amazement of his existence.