When you look at a drawing of the Penrose Triangle, you see a triangle surrounded by planes. At first glance, it looks as if it could exist off the page and outside the imagination. But take a second glance.
It’s those planes that are the problem. If you try to recreate the triangle as a solid object the sides do not meet – at least not without some considerable manipulation.
On the other hand, the illusion that they do meet makes them a wonderful jumping off point for the artistic imagination, as in Escher’s “House of Stairs” or “Reality”. Take a look – and enjoy the exploration of this illusion!