in Thoreau’s Journal:

It is glorious to be abroad this afternoon, the snow melts on the surface; the warmth of the sun reminds me of summer….Ah then, the brook beyond, its rippling waters and its sunny sands. They made me forget it was winter….

The sun reflected from the sandy, gravelly bottom, sometimes a bright sunny streak no bigger than your finger reflected from a ripple as from a prism, and the sunlight reflected from a hundred points of the surface of the rippling brook, enabled me to realize summer…