And, again, their coming and going, how curious and suggestive! We go out in the morning, and no Thrush or Vireo is to be heard; we go out again, and every tree and grove is musical; yet again, and all is silent. Who saw them come? who saw them depart? This pert little Winter-Wren, for instance, darting in and out the fence, diving under the rubbish here and coming up yards away,--how does he manage with those little circular wings to compass degrees and zones, and arrive always in the nick of time? Last August I saw him in the remotest wilds of the Adirondack, impatient and inquisitive as usual; a few weeks later, on the Potomac, I was greeted by the same hardy little busybody. Does he travel by easy stages from bush to bush and from wood to wood? or has that compact little body force and courage to brave the night and the upper air, and so achieve leagues at one pull? And yonder Bluebird, with the hue of the Bermuda sky upon his back, as Thoreau would say, and the flush of its dawn upon his breast,--did he come down out of heaven on that bright March morning when he told us so softly and plaintively, that, if we pleased, spring had come? About the middle of September I go out in the woods, and am attracted by a faint piping and lisping in the tops of the Oaks and Chestnuts. Tiny figures dart to and fro so rapidly that it pains the eye to follow them, and I discover that the Black-Poll Warbler is paying me a return visit. Presently I likewise perceive a troop of Redstarts, or Green-Backed Warblers, or Golden and Ruby-Crowned Wrens, flashing through the Chestnut-branches, or hanging like jewels on the Cedar-sprays. A week of two later, and my darlings are gone, another love is in my heart, and other voices fill my ears. But so unapparent and mysterious are the coming and going, that I look upon each as a special Providence, and value them as visitants from another sphere. The migration of the Pigeons, Ducks, and Geese is obvious enough; we see them stream across the heavens, or hear their _clang_ in the night; but these minstrels of the field and forest add to their other charms a shade of mystery, and pique the imagination by their invisible and unknown journeyings. To be sure, we know they follow the opening season north and the retreating summer south; but who will point to the parallels that mark the limits of their wandering, or take us to their most secret haunts? What greater marvel than this simple gift of music? What beside birds and the human species sing? It is the crowning gift; through it the field and forest are justified. Nature said, "These rude forms and forces must have a spokesman of their own nursing; here are flowers and odor, let there be music also." I suspect the subtile spirit of the meadow took form in the Bobolink, that the high pasture-lands begot the Vesper-Sparrow, and that from the imprisoned sense and harmony of the forests sprang the Wood-Thrush.