Three canons set three verses from Luke's account of the Annunciation, starting with the words of the title and ending Be it unto me according to thy word. The canons are strict, so all four parts can be learnt by voices in unison, with a range from A flat below middle C up to the F an octave and a sixth above. Or an octave lower for men, since singers can be upper or lower voices, or mixed, or different combinations of voices on different parts. So far, so flexible. What isntflexible are the notes and rhythms themselves, where there is a delightful rhythmic fluidity. With a 15/8 time signature, each canon starts as if in lilting compound time, alternating quavers and crotchets, but after a bar or so, passages of quavers beamed in pairs gently cut across the dotted crotchetbeat. As the four parts overlap, what seems comparatively straightforward to learn sounds fascinatingly complex in performance.