I was at a colleague’s apartment for the first time recently and was sitting facing a white wall on which was painted a lovely, pale grey image of the upper branches of a tree. An hour or so later, I noticed that the shadow cast on the same wall by the tree outside her window had a very similar form, and as I watched, it came closer and closer until it finally clicked, a perfect fit, you could almost hear it, but just for an instant, and then it moved on. When I mentioned it to her later, she exclaimed, “Ah yes! It happens only once a year, and I forgot that it was today.”

And oddly enough, I have another friend who also has the shadow of a tree painted in faint grey on a white wall. It’s the silhouette of a cherry tree in flower, but the tree outside the window, which casts its shadow on the wall every afternoon, is a parasol pine, so the beauty in this case is based entirely in disparity.