Unlike MacMillan's first three symphonies Symphony no 4 (2014-15) is essentially abstract. Here he is interested in the interplay of different types of material, following upon a fascination with music as ritual that has stretched from Monteverdi in the early 17th century through to Boulez and Birtwistle in the present day. There are four distinct archetypes in this work, which can be viewed as rituals of movement, exhortation, petition and joy. It is also a homage to Robert Carver (c1487-after 1566), the most important Scottish composer of the High Renaissance. There are allusions to Carver's 10-voice Mass Dum sacrum mysterium embedded in the symphony, and at a number of points it emerges from across the centuries in a more discernible form: the vocal lines are muted and muffled, literally in the distance, as they are played delicately by the back desks of the violas, cellos and double basses.