From website: "Three little houses stand near one another, each under a crossvaulted roof. We have an exterior view of the left-hand house, and interior view of the right-hand one and an either exterior or interior view of the one in the middle, according to choice. There are several similar inversions illustrated in this print; let us describe one of them. Two boys are to be seen, playing a flute. The one on the left is looking down through the window on to the roof of the middle house; if he were to climb out of the window he could stand on this roof. And then if he were to jump down in front of it he would land up one storey lower, on the dark-coloured floor before the house. And yet the right-hand flautist who regards that same cross-vault as a roof curving above his head, will find, if he wants to climb out of his window, that there is no floor for him to land on, only a fathomless abyss."
Convex and Concave
