Sandro del Prete

Horses usually take hurdles in a jump. In this illustration, two boys have jumped over the fence on a wooden horse. Despite its inability to move, the horse succeeds in taking its riders into the neighbour's garden, imitating its notorious ancestor from mythical Troy.

The four horizontal boards are superimposed on the pickets in a vertical pattern, though the horse's "belly" crosses them on a horizontal plane. To be feasible, the lowermost boards need to occupy the same height as the uppermost ones while simultaneously running parallel to each other in a straight line. Cover either end of the fence to see the visual paradox. The boards are aligned both horizontally and vertically. This illustration is based on the impossible triangle.