A smooth, glassy mirror, reflecting the light sky and the dark and shady woods.

June 11.

To Framingham with Mrs. Brown. All day cloudy and cool without rain. At twelve walk up the Sudbury River above Frank's to Ashland, at first through the meadows, then over the high hills in the vicinity. From a high hill on the west of the river, about a mile from Frank's, get a good view of Farm Pond eastward, which empties into the river, with South Framingham on the south east side of it. I do not instantly detect it, the dark hills and trees being reflected in it. 

How agreeable in a still, cloudy day, when large masses of clouds, equally dispersed, float across the sky, not threatening rain, but preserving a temperate air, to see a sheet of water thus revealed by its reflections, a smooth, glassy mirror, reflecting the light sky and the dark and shady woods. It is very much like a mirage.

H. D. Thoreau, Journal, June 11, 1854

A smooth, glassy mirror, reflecting the light sky and the dark and shady woods. See August 6, 1860 ("We distinguish the reflections of the woods perfectly in ponds three miles off. “)