Near the end of Walden, in "The Pond in Winter" Henry David Thoreau reports his observation of an optical-geometrical phenomenon that by chance I noted in a shiny corridor a few years ago:

... Sometimes, also, when the ice was covered with shallow puddles, I saw a double shadow of myself, one standing on the head of the other, one on the ice, the other on the trees or hillside. ...

(cf. UpsideDownShadows (2007-11-29)) - ^z - 2009-10-02