“The monkey with glasses that reads”. Orvieto, MODO (Museum of the Opera of the Duomo of Orvieto): Alberi Library, a cycle of monochrome frescoes where famous classical masters of different subjects are represented (law, medicine, astronomy, grammar), attributed to Luca Signorelli's pupils, 1501-1503: detail of the most famous and most curious drawing of the monkey with glasses that opens a book where the phrase "Legere et non intelligere est negligere" appears (Reading and not understanding is equivalent to not reading). A moral maxim of an anonymous author dated approximately around the third century and become very famous in schools, especially for students of Latin grammar.