This rise and fall of Walden at long intervals serves this use at least; the water standing at this great height for a year or more, though it makes it difficult to walk round it, kills the shrubs and trees which have sprung up about its edge since the last rise⁠—pitch pines, birches, alders, aspens, and others⁠—and, falling again, leaves an unobstructed shore; for, unlike many ponds and all waters which are subject to a daily tide, its shore is cleanest when the water is lowest. On the side of the pond next my house a row of pitch pines, fifteen feet high, has been killed and tipped over as if by a lever, and thus a stop put to their encroachments; and their size indicates how many years have elapsed since the last rise to this height. By this fluctuation the pond asserts its title to a shore, and thus the shore is shorn