Mahler (who regarded Bruckner as his master and “forerunner”) once told Sibelius that a symphony should be a whole world, able to accommodate absolutely everything the composer can pour into it. For Mahler, this meant symphonies that are defiantly incongruous, enormous metropolitan farragoes of disparate parts, always somewhat ironic (even at their most pompous junctures), buoyant and wild, but sophisticated and whimsical too, and shot through with Viennese urbanity.