Dialogue: “a verbal interchange, conversation between two or more persons … a composition for two or more voices or instruments”. Intelligence, logic and reason all have a part to play, not only in human conversation, but also in musical dialogues, through simplicity of expression, hexachordal mutation of Gregorian chant, well-considered responses to musical cues, and so on.

These dialogues for two organs originate in part from the practice of alternatim, in which the instrument would both add to and draw inspiration from a complex polyphonic texture. Organ improvisation is moreover centuries-old, as shown by this reference made to it by Girolamo Diruta (c.1550- after 1612) in his organ treatise Il Transilvano: “… listening in St Mark’s (Venice), that most famous of churches, to a duel between two organs responding to one another with such skill and grace that I was