in Thoreau’s Journal:

We go seeking the south sides of hills and woods, or deep hollows to walk in, this cold and blustering day. We sit by the side of little Goose Pond to watch the ripples on it. Now it is merely smooth, and then there drops down upon it, deep as it lies amid the hills, a sharp and narrow blast of the icy north wind careering above, striking it perhaps by a point or an edge, and swiftly speeding along it, making a dark blue ripple…

You could sit there and watch these blue shadows playing over the surface like light and shade on changeable silk, for hours…Watching the ripples fall and dark across the surface of low-lying and small woodland lakes is one of the amusements of these windy March and April days.