Pacioli completed another equally playful book at about the same time:De Viribus Quantitatis (‘On the powers of numbers’), which compilesnumber games, card tricks, riddles and reasoning problems. It makesfrequent mention of Leonardo, and much of the content overlaps withpuzzles that can be found in the notebooks.

In February 1498, Maestro Lucacompleted De Divina Proportione, which was illustrated by ‘the graciousleft hand’ of his new friend, as Leonardo showed off his mastery ofperspective and geometry with a set of precise, fenestrated illustrations ofthe six Platonic solids, from the four-faced tetrahedron to the twenty-sidedicosahedron.

Pacioli’s reader, in whose company he would spend most of thefollowing decade, was Leonardo da Vinci.