Musical motives in Peter Grimes are utterances, in the sense that they appear first as musical vehicles for the texted vocalizing of stage characters. Characteristic melodic shapes set sung text, as speech acts, and continue, by their returns, to exert an illocutionary force that is precise, if not entirely fixed. It is only when the orchestra abandons an accompanimental role for a more autonomous thematic “voice” of its own, that motives assume a force of utterance largely independent of the singers. Such wordless moments deepen the semantic charge of a melodic shape, imbuing it with a mysterious presence, an identity of its own. When the orchestral passacaglia magnifies Peter's Prayer motive by obsessive repetition, the prayer comes to stand outside the action, at a remove that opens up a discursive space within which musical drama can operate on a level independent of text-bound expression of a local situation.

Motive, in Billy Budd, is a more diverse, intricate, and problematic concept than in Grimes. It is less directly associated with vocal utterance, and more often an agent of abstract conceptual, even metaphysical reference. It is by musical motive that the threat of Mutiny weaves its way into the operatic score as a distinct presence; equally, in Act 2, the innately elusive Mist – an image only glimpsed in the novel – looms larger in the opera by its motivic identity.