“Fold by fold” – this is the English translation of the French title; the text was written by Stéphane Mallarmé – is a milestone in recent music history: in this work, Mallarmé – the revolutionary innovator of French poetry – meets Pierre Boulez, whose treatment of the text and instruments reveals him to be just as much a revolutionary innovator of music. Pli selon pli is therefore not just a “Portrait de Mallarmé”, but also one of Pierre Boulez.