Laudator Temporis Acti

Henry David Thoreau, Walden, chapter 17 (Spring):

The first sparrow of spring! The year beginning with younger hope than ever! The faint silvery warblings heard over the partially bare and moist fields from the bluebird, the song sparrow, and the red-wing, as if the last flakes of winter tinkled as they fell! What at such a time are histories, chronologies, traditions, and all written revelations? The brooks sing carols and glees to the spring. The marsh hawk, sailing low over the meadow, is already seeking the first slimy life that awakes. The sinking sound of melting snow is heard in all dells, and the ice dissolves apace in the ponds. The grass flames up on the hillsides like a spring fire,—"et primitus oritur herba imbribus primoribus evocata,"—as if the earth sent forth an inward heat to greet the returning sun; not yellow but green is the color of its flame;—the symbol of perpetual youth, the grass-blade, like a long green ribbon, streams from the sod into the summer, checked indeed by the frost, but anon pushing on again, lifting its spear of last year's hay with the fresh life below. It grows as steadily as the rill oozes out of the ground. It is almost identical with that, for in the growing days of June, when the rills are dry, the grass-blades are their channels, and from year to year the herds drink at this perennial green stream, and the mower draws from it betimes their winter supply. So our human life but dies down to its root, and still puts forth its green blade to eternity.

It is interesting to compare a earlier version of this passage, from Thoreau's Journal (Sept. 29, 1843):

The first sparrow of spring! The year beginning with younger hope than ever. The first silvery warblings heard over the bare and dank fields, as if the last flakes of winter tinkled as they fell. What, then, are histories, chronologies, and all written revelations? Flakes of warm sunlight fall on the congealed fields. The brooks and rills sing carols and glees for the spring. The marshhawk already seeks the first stirring life that awakes. The sough of melting snow is heard in all dells, and on all the hillsides, and by the sunny river-banks; and the ice dissolves in the ponds. The earth sends forth, as it were, an inward heat; not yellow like the sun, but green is the color of her flames; and the grass flames up on the warm hillsides as her spring fire. Methinks the sight of the first sod of fresh grass in the spring would make the reformer reconsider his schemes; the faithless and despairing man revive. Grass is a symbol of perpetual growth,—its blade like a long green ribbon, streaming from the sod into the summer, checked indeed by the frost, but anon pushing on again, lifting its last year's spear of withered hay with the fresh life below. I have seen when early in spring the clumps of grass stood with their three inches of new green upholding their withered spears of the last autumn. It is as steady a growth as the rill which leaps out of the ground,—indeed it is almost identical with that; for in the vigorous fertile days of June when the rills are dry, the grass-blades are their only channels. And from year to year, the herds drink this green stream, and the mower cuts from the out-welling supply,—what the several needs require. So the human life but dies down to the surface of Nature; but puts forth its green blade to eternity.

This passage doesn't seem to be in the Torrey-Allen edition of Thoreau's Journal. I found it in Carl Bode's Selected Journals of Henry David Thoreau. Bode cites as his source F.B. Sanborn's The First and Last Journeys of Thoreau (1905), vol. 1.