The Liber Ordinarius from the cathedral of Padua (Biblioteca Capitolare, cod. E 57, second half of the 13th century) is an extraordinary source. It outlines, with a wealth of particulars, the distinctive character of the Paduan liturgy; it provides detailed testimony concerning performances of remarkable complexity (for example, the tropes and sequences, or the dramatic Offices); and it even gives some indications for “stage directions”. This wealth of information was probably intended for the chorarii, that is to say, the magister scholarum and the cantor, to whom fell the task of conducting the rites, and it efficaciously expands upon and specifies the principal function of this liturgical book: that of gathering together in an orderly fashion, or rather according to the liturgical order of the feasts, whatever was to be recited, sung or simply executed during the year. For this reason, readings, songs and prayers can only be referred to by the first words of the text; only in a few cases are they accompanied by music and it too is limited to the incipits.