in Thoreau’s Journal:

Walden froze over apparently last night. It is but little more than an inch thick—& 2 or 3 square rods by Hubbards shore are still open. A dark transparent ice— It would not have frozen entirely over as it were in one night or may be a little more and yet have been so thin next to the shore as well as in the middle, if it had not been so late in the winter, & so ready to freeze. It is a dark transparent ice. But will not bear me without much cracking.

and

from “The Ponds” in Walden:

Why, here is Walden, the same woodland lake that I discovered so many years ago; where a forest was cut down last winter another is springing up by its shore as lustily as ever; the same thought is welling up to its surface that was then; it is the same liquid joy and happiness to itself and its Maker, ay, and it may be to me. It is the work of a brave man surely, in whom there was no guile! He rounded this water with his hand, deepened and clarified it in his thought, and in his will bequeathed it to Concord. I see by its face that it is visited by the same reflection; and I can almost say, Walden, is it you?