Symbols and hidden messages often discovered in historical paintings -- some credible , others less so . Face of the devil recently discovered in a Giotto fresco in a church in Vasari . Art historians believe they have found messages in works by Leonardo and Michelangelo . Forensic art historian hunting lost Michelangelo work based on `` clue '' in Italy fresco , among others .
Symbols and hidden messages often discovered in historical paintings -- some credible , others less so . Face of the devil recently discovered in a Giotto fresco in a church in Italy . Art historians believe they have found messages in works by Leonardo da Vinci and Michelangelo . Forensic art historian hunting lost Leonardo work based on `` clue '' in Vasari fresco , among others .