Phrase plus ratio quam vis is an expression that thanks to Prof. Karol Estreicher (junior), was adopted in 1964 as a motto of the Jagiellonian University. It also became the main theme of the 72nd Session of the Société Internationale Fernand de Visscher pour l’Histoire des Droits de l’Antiquité (SIHDA), which was held in September 2018 in Cracow and was organised by Prof. Franciszek Longchamps de Bérier. Phrase plus ratio quam vis derives from a poem preserved under the name of Maximianus, who was an elegiac poet of the 6th century AD. In the poem, the author describes the state of mind of an aging man left by a lover. Plus ratio quam vis, which is a motto of the Cracow’s Alma Mater and the 72nd Session of SIHDA, is neither a legal maxim nor is related to youth education. The expression plus ratio quam vis has its origins, not in the treasury of legal knowledge, but erotic one. However, it is so broad in its scope that it could become the motto of the oldest Polish University, as well as the main theme of one of the most significant international meetings of Romanists and Historians of ancient laws.