Two-part compositions were one of the main means through which music was taught during the Renaissance and Baroque periods, and they therefore played an important role in preparing both professional and amateur musicians. This site deals with the duos published in dedicated collections and treatises ranging in date from 1521, the year when the first collection was issued (Eustachio Romano's), to 1744, the date of publication of Angelo Michele Bertalotti's Solfeggi. The importance of duos during this period is evidenced by the number of extant collections – more than sixty in Italy alone – and these publications reveal an essential continuity in the teaching of music theory and practice over a period of 250 years. During this period all two-part didactic music served consistent and well-defined functions: the teaching of note-values and solmization; the teaching of modality and composition; as the basis for practising both vocal and instrumental music. | 
