Since Roman times, the word mathematici had applied especially to mathematicians, and in the thirteenth century Roger Bacon still strove at length to convince his audience of the difference between false mathematics and true mathematics. Boethius produced an influential Latin work on arithmetic, which was closely based on the Greek Introduction to Arithmetic of the neo-Pythagorean Nicomachus of Gerasa and also a substantial treatise on music, a science that was then regarded as intimately dependent upon arithmetic. Geometrical figures themselves could perform important semiotic functions, as when in the fourteenth century Nicole Oresme used graphic-like diagrams to symbolize variations of speeds and qualities. In standard histories of mathematics, the name of Jordanus de Nemore is linked with that of Leonardo of Pisa as another medieval mathematician of undoubted originality. A striking feature of medieval mathematics, especially in its theoretical genre, is the amount of discussion that was conducted in terms of ratios and their equalities or proportions.