impossible triangle, after apprehension of the perceptively given mode of being of that 'object', the visual system assumes that all three sides touch on all three sides, whereas this happens on only one side. In fact, the sides touch only optically, because they are separate in depth. In Meinong's words, Penrose's triangle has been inserted in an 'objective', or in what we would today call a "cognitive schema". Re-examination of the Graz school's...