Leonardo wrote on a sheet of the Codex Atlanticus several personal notes regarding his forthcoming book, De ludo geometrico: among the topics listed were thirteen graphic (not arithmetic) solutions to squaring the circle. Intellectual interest in squaring, which had been high for centuries, came to an abrupt halt in 1882 when Ferdinand von Lindemann, a scientist and professor at the University of Königsberg, demonstrated that squaring the circle is impossible, arguing that the constant π, the ratio of a circle’s circumference to its diameter, is an irrational number.
