Into the upper end of Chocorua Lake flows a brook of transparent water, fed by melting snows, out of “the heart of the mountain.” Along this the song of the water thrush leads the wanderer from one limpid pool to another, a song that has in it some of the liquid prattle of the stream but more of a dominant, aggressive note that carries far. There is a touch of sunlight in the color of the water thrush’s breast, sunlight flecked with little brown shadow markings that are like the uniform brown of his back, and if it were not that he sticks so closely to the water he might suggest the oven-bird to the careless glance. There is something of the song sparrow and the oven-bird at once in his song. It is as if the two birds had mated to produce him and the singing masters of both families had had the youngsters to singing school. Up this clear-water brook the oven-birds call you by way of the height of land, the water thrushes from pool to pool, while the sun drops behind Paugus in mid afternoon, and the blue shadows of the Sandwich range add to the cool gloom which wells upward from the deep gorge which is the heart of the mountains. On the way, as the water thrushes and Maryland yellow-throats sing from the thickets near the water, so the oven-bird sends his aggressive staccato from the middle distances of the higher trees. I never knew an oven-bird to sing from either a treetop or a low thicket. Always he sits on a limb well up the trunk yet well beneath the shade also, and sends forth that aggressive, eager call for knowledge. “Teach us, teach us, teach us,” he cries to the wood gods, nor is he ever satisfied with his schooling, but applies persistently for more. The oven-bird is the very voice of the spirit of modern learning, crying always, in the wilderness of knowledge attained, for more knowledge. The wood gods have taught him much. Invisibility for himself he has almost learned. He sits like a knot on a speckled brown limb, and his speckled brown breast is so much like it that he may sing long there within a little distance of your eye before you see him. Invisibility for his nest he and his demure brown wife have learned completely. You may sit on it to rest among the brown leaves in the wood and not know it is there; unless the frightened escape of the brown mother birds gives you a hint, and even then it is invisible, so completely is it hidden in the debris dropped by the previous autumn. Of dead weed stalks, grasses and brown leaves it is not only built but roofed, and with an entrance on one side that to the uninitiated might be an entrance to the nest of a field mouse, indeed, but never that to a bird’s nest. It is not for greater knowledge of nest hiding that the oven-bird need pray to the wood gods, nor may we know what further wisdom he seeks, but all summer long he asks for it in no uncertain tones.