Some of Leonardo's philosophies can be found in a series of fables he wrote for the court of Ludovico Sforza. These were presented as jests (labelled 'prophecies') in which he told a riddle and made his audience guess the title. Prevalent themes include the dangers of an inflated sense of self-worth, often as described in opposition to the benefits that one can gain through awareness, humility and endeavour. Leonardo also had a distinctive sense of humour, showing newfound friends a lizard he had decorated in scales, a horn and beard made from quicksilver to surprise them, and describing a practical joke in his "Treatise on Painting":