Recently I received several questions about Trompe l’oeil, so I decided to revisit that topic. Easy to do because it’s a favorite of mine. I enjoy almost anything about the brain and this is about the brain. The question is: does your eye really see what is actually there? Although you are certain it does, maybe not. Trompe l'œil is an art technique that uses realistic imagery to create optical illusions that the objects or landscapes depicted are three dimensional. Many of them actually exist on a flat surface, however. (You may have seen this in some sidewalk murals.) Dating from before the Baroque period, murals from Greek and Roman times were known to exist in places such as Pompeii, where a typical trompe l'œil mural might depict a window, door, or hallway, intended to suggest a much larger room. There is an old Greek story that purports a contest between two renowned painters: Zeuxis (born around 464 BC) and Parrhasius, a rival artist. Zeuxis produced a still life painting so convincing that birds flew down to peck at the painted grapes. Parrhasius asked Zeuxis to judge one of his (Parhasius’) paintings that was behind a pair of tattered curtains in his study. Parrhasius asked Zeuxis to pull back the curtains, but when Zeuxis tried, he could not, because the curtains were Parrhasius’s painting. Of course, that made Parrhasius the winner. More tomorrow.