Rithmomachia

Rithmomachia — the “battle of numbers” — was, for five centuries, the philosophers’ game of European universities. Devised in the eleventh century by a Benedictine schoolmaster and elaborated through the Renaissance by Faber, Boissière, and Selenus, it was played on an extended chessboard with pieces marked by triangular, square, and round Pythagorean numbers. Capture proceeded by arithmetical relation; victory came in tiers (Magna, Major, and the most coveted Excellentissima) determined by the harmonic, arithmetic, and geometric proportions one could compose with one’s captured pieces. To play Rithmomachia was to enact, in miniature, the medieval conviction that number was the structure of the cosmos. The Academy hosts the game in tribute to that conviction — and as a working tool for any Fellow who wishes to feel, with their hands, what it once meant to do philosophy through play.

First codified around 1030 by Asilo (later bishop of Würzburg) and developed in the cathedral schools of Liège and Reichenau. Survived in printed editions through the seventeenth century; rediscovered by Ann Moyer’s 2001 study The Philosophers’ Game. The Academy’s federated implementation follows Boissière’s 1556 ruleset by default.