The composer and theorist Johannes Tinctoris provided the most rigorous definition of contrapuntal practice
available in the second half of the fifteenth century. Buried within his De arte contrapuncti (1477) is a small
number of progressions in oblique motion that define a new analytical concept: contrapuntal direction. These
few cases share the peculiar quality of identifying the function of each voice in the progression. The
contrapuntal voice must always move towards the stationary tenor since Tinctoris does not permit the same
sounding result when the tenor moves towards the contrapuntal voice.

Contrapuntal direction provides a valuable tool for diagnosing contrapuntal relationships in complex
polyphony. In this paper, I employ a series of examples from the early L’homme armé mass repertoire to
demonstrate that contrapuntal direction can clarify the compositional structure of late fifteenth-century
polyphony, including passages without cantus firmus. I focus special attention on the implications of cases
where composers seem not to be following Tinctoris’s teaching. While posing a series of questions for further
research, contrapuntal direction provides an important step towards developing a generative theory of fourvoice
cantus firmus texture.