Let's go back to Aschenbach's infamous stranger god dream. What is that all about? The "stranger, the enemy of the serene and dignified intellect," appears in Aschenbach's dream amidst an orgiastic festival with horned people, smelly goats and an "obscene symbol"—a wooden pillar shaped like a phallus (4.37). Well, it seems pretty clear that this is a sexual dream (the revelers end the night in "unbridled coupling"), but as for the "stranger god, "what's the deal?
Here's the lowdown: The stranger is another name for the god Dionysos—this is how he's known in Euripides' s The Bacchae, a play that deals with the life story of Dionysos and the cult that surrounded him. So the stranger god in our novella, then, is a shout-out to Dionysos, a most debaucherous god—his arenas are wine, theater, and parties—but by calling him "the stranger," Dionysos is also linked with foreignness, to the unknown. The "stranger god," then, symbolizes everything that draws Aschenbach from his everyday life in search of the exotic.
As we talk about at the beginning of this section (check out our thoughts on mythological figures), Nietzsche's The Birth of Tragedy (1875) argues that the pre-classical cult of Dionysos—which involved festivals reimagined in Death in Venice pretty dramatically—was the origin of refined, classical Greek tragedy.
So when we read that the stranger god is "the enemy of the serene and dignified intellect," we're also being told that this is Nietzsche's Dionysos, a symbol, not just of something foreign and "other," but one representing all the dark and "primitive" elements that lurk in the shadows of European civilization. The "stranger god," then, both represents Aschenbach's undoing as well as the fact that, though it feels surprising and foreign, this undoing has actually always been present. Because nothing says ever-present like the word god.