Word setting in Machaut's refrain songs poses a problem, for whilst it is clearly indicated in the manuscripts, it often does not comply with recognised principles or values. To understand the situation, a dualistic relationship of words and music is proposed. It is founded in the coordinated but independent operation of principles of musical mimesis and musico-poetic dislocation. The music is constructed at a primary level as an imitation of the poetic form; but it is fundamentally independent of this model and may thus be detached from it and displaced against it. Devices such as ‘cross-cadencing’, ‘quasi-declamation’, ‘complementary-cadence inversion’ and ‘dissonance’ between implied and actual word setting are manifestations of this technique. The proposal accounts on the same basis for both the close relationship of words and music observable in the virelais and for the more abstract connection apparent in the rondeaux. There is a technical unity at work across the genres in Machaut's song composition.