tactus

Tactus is a term used in Western music theory to denote the regular pulse or beat that underlies much medieval and Renaissance rhythmic practice. The word is derived from Latin tactus, and the concept refers to a steady tempo that performers strive to maintain, providing a framework for timing and proportion.

Historically, tactus functioned as the underlying time unit in mensural notation. It could be felt as a steady beat that subdivided into two (duple) or three (triple) subdivisions, giving rise to binary and ternary rhythmic relationships. The exact value of the tactus varied across periods and regions, and treatises described it as something singers, dancers, or instrumentalists would perceive and reproduce colloquially or by gesture, rather than as a fixed metronomic marking.

In practice, tactus organized how music was performed. It guided tempo, mensural proportions, and the alignment of rhythmic values within phrases. A conductor, leader, or designated player would gesture or beat the tactus to keep the ensemble together, especially in complex polyphony or proportional notation. As notation evolved, the explicit use of tactus diminished, but the notion of an underlying beat persisted and influenced later tempo concepts.

In modern musicology, tactus remains a useful concept for studying early music performance practice. It helps explain how rhythms were interpreted, how tempo could vary within a piece, and how different mensural systems relate to each other. While the term is less common in contemporary notation, it remains a key analytic tool for understanding the time structure of medieval and Renaissance repertoires.