The three most moving, transporting death scenes in 19th-century opera all involve the respective heroines mounting a funeral pyre — partly, no doubt, a matter of operatic convention and fashion, but also recalling opera to its duty as a rite of purification. Berlioz’s Didon in Les Troyens, like her creator, is so relentless in her grasp of the truth that she fails to achieve anything but a vision of Carthage overcome by Rome, and ends in despair and execration.