What is the main conflict in The Magic Mountain by Thomas Mann?

In Nietzsche's influential book, The Birth of Tragedy, he interprets ancient Greek culture in terms of a conflict between two fundamental forces. He named one force Apollonian after Apollo, the Greek god of harmony, proportion, reason, architecture, the sun, and the Dorian mode in Greek music. The other force he called Dionysian, after Dionysios, the god of wine, uncontrolled emotion, night, drunkenness, divine madness, ecstasy, loss of self, and the Mixolydian mode in Greek music. The conflict between these two forces is the major theme of The Magic Mountain.