But glass or no glass, how could an ornithological observer, whose power—so Emerson said—"seemed to indicate additional senses," be in the field daily for ten or fifteen years before setting eyes upon his first rose-breasted grosbeak?—which memorable event happened to Thoreau on the 13th of June, 1853! How could a man who had made it his business for at least a dozen years to "name all the birds without a gun," stand for a long time within a few feet of a large bird, so busy that it could not be scared far away, and then go home uncertain whether he had been looking at a woodcock or a snipe? How could he, when thirty-five years old, see a flock of sparrows, and hear them sing, and not be sure whether or not they were chipping sparrows? And how could a man so strong in times and seasons, always marking dates with an almanac's exactness, how could he, so late as '52, inquire concerning the downy woodpecker, one of the more familiar and constant of year-round birds, "Do we see him in the winter?" and again, a year later, be found asking whether he, the same downy woodpecker, is not the first of our woodland birds to arrive in the spring? At thirty-six he is amazed to the extent of double exclamation points by the sight of a flicker so early as March 29. It fills one with astonishment to hear him (May 4, 1853) describing what he takes to be an indigo-bird after this fashion: "Dark throat and light beneath, and white spot on wings," with hoarse, rapid notes, a kind of _twee, twee, twee,_ not musical. The stranger may have been—most likely it was—a black-throated blue warbler; which is as much like an indigo-bird as a bluebird is like a blue jay,—or a yellow apple like an orange. And the indigo-bird, it should be said, is a common New-Englander, such as one of our modern schoolboy bird-gazers would have no difficulty in getting into his "list" any summer day in Concord; while the warbler in question, though nothing but a migrant, and somewhat seclusive in its habits, is so regular in its passage and so unmistakably marked (no bird more so), that it seems marvellous how Thoreau, prowling about everywhere with his eyes open, should year after year have missed it. The truth appears to be that even of the commoner sorts of birds that breed in eastern Massachusetts or migrate through it, Thoreau—during the greater part of his life, at least—knew by sight and name only a small proportion, wonderful as his knowledge seemed to those who, like Emerson, knew practically nothing.[2]