PT Journal AU Otisk, M TI Rithmomachia - the Battle of Numbers, i.e. the Arithmetical Game of Philosophers SO Aither PY 2015 BP 118 EP 139 VL 7 IS 2 DI 10.5507/aither.2015.018 AB This paper deals with the philosopher's game called rithmomachia, i.e. the battle of the numbers. The beginnings of the playing of this game we can find around the year 1000 AD, the oldest texts are dated to the first half of the 11th century. The aim of this paper is the description of selected rules of this game according to the oldest texts about rithmomachy (written between ca. 1030 and ca. 1130). This article mainly wants to focus on the correlation between those rules and the subject of interest of the medieval intellectuals in the field of arithmetic (especially in the context of Boethius's Introduction to Arithmetic). ER