Two motets composed by Heinrich Isaac around 1500—Inviolata integra et casta es Maria and Alma redemptoris mater—exemplify compositional techniques used by Isaac and his contemporaries to combine newer styles of imitative polyphony with the older cantus firmus practice. Between the two motets, three approaches to the cantus firmus are demonstrated: canonic cantus firmus, long-note cantus firmus, and chant paraphrase. The structure of Inviolata is based on modules comprising the canonic cantus firmus and other repeated melodies. The cantus firmus is a light paraphrase of the original sequence. The strict, regular module structure allows for the recreation of the missing contratenor 2 part with very little free counterpoint. Isaac also uses a module structure for Alma redemptoris mater, the cantus firmus of which alternates between paraphrase and long-note treatment. In this case, most modules come in the form of chunks of four-voice music repeated exactly, repeated and transposed, or cadential formulas. Non-imitative modules of paired voices are also used. In addition to these modules, Isaac uses non-modular compositional techniques such as stretto fuga. Beyond these small-scale compositional devices, both motets exhibit large-scale formal structures through repetition. By extrapolating Isaac’s possible compositional process from the modular construction of these two motets, it can be concluded that his process of composing with a cantus firmus is very similar to his composing without a cantus firmus.

Works: Heinrich Isaac: Inviolata integra casta es Maria (235-46), Alma redemptoris mater (246-63).

Sources: Anonymous: Inviolata integra casta es Maria (235-46), Alma redemptoris mater (246-63).

Index Classifications: 1500s

Contributed by: Matthew Van Vleet