Our picture of musical training in the Middle Ages and Renaissance is frustratingly generic and fragmentary. The musicians of that era – it is often stated – were well versed in the method of the so-called Guidonian hand, by which the twenty pitches of the gamut (often referred to as claves) were mapped onto the joints of the left hand along with the six voces ut, re, mi, fa, sol, la, dating back to Guido of Arezzo’s Epistola ad Michahelem (c. 1033). Professional singers learnt how to group the claves into overlapping hexachords in the early stages of musical training and referred to the musical hand as a mnemonic aid while sight-singing. By the early fourteenth century at the latest, a sophisticated set of rules of behaviour was in place that allowed practical musicians and theorists to connect the six syllables to the claves and to perform hexachordal mutations smoothly and effectively.