Dux

What it means

Dux, Latin for “leader,” refers in a fugue to the very first statement of the subject, presented by the first entering voice in the work's home key. It opens the fugue's exposition and establishes the melodic and rhythmic material that the following voices take up in imitation.

Musical use

After the dux, the second entering voice answers with the so-called comes, usually a version of the same subject transposed to the dominant key, while the dux continues in the first voice with a countersubject. This interplay of dux and comes continues until every voice of the fugue has entered once and the exposition is complete.

The dux should be distinguished from the comes, which takes up the same thematic material but sounds in a different key and therefore fulfils a different harmonic function. In later development sections of a fugue, the subject can be reintroduced in further keys as a kind of renewed dux, without the original home key necessarily having to return.

Performance practice

When listening to a fugue, first identify the dux in the opening voice, since it determines the entire later network of relationships among the voices, then follow how each subsequent voice takes up the subject as comes or as a renewed dux. When performing yourself, it helps to bring out the dux's entries slightly in tone, so listeners can clearly perceive the fugue's underlying structure.