But I, being poor, have only my dreams. I have spread my dreams under your feet. Tread softly, because you tread on my dreams... So begins Deborah Warner’s captivating 2008 production of Purcell’s timeless opera Dido and Æneas: a careful warning that suits the tragic story only too well. Swedish mezzo-soprano Malena Ernman as a disarming Dido is at the head of a stellar cast joined by Les Arts Florissants under William Christie’s direction.