Treatise by Benedetto Varchi on proportion as the basis for rithmomachia, a mathematical game played on a chessboard with pieces that each have a shape and a number; a dialogue written by Carlo di Ruberto Strozzi, in which Cosimo Rucellai, who introduced the game to Benedetto Varchi, teaches the rules to Strozzi and Jacopo di Piero Vettori; and other notes on the game. Later unrelated notes and pen trials on leaves before and after main texts. Damage and bleed-through due to oxidation on many leaves.