If we could divide books into two genres, Odyssey books and Iliad books, Siddhartha would be an exemplary Odyssey book. However, Siddhartha departs from Odysseus. He goes on a circular journey, encounters isolation, a courtesan and a wealthy merchant. He is detained by water and eventually realises that the world is an illusion to be detached from. Odysseus wants no such detachment. Hesse’s biggest argument here is against modern individualism, of which the Odyssey is the founding myth.
Siddhartha is like a well researched, post-Enlightenment version of Rasselas. I think of it as, in some ways, the opposite of Ulysses. It is no surprise that Hesse spent time in an asylum when he was young and spent periods of his life in isolation. Like many other Western wisdom-literature books (think Thoreau) this is a late-Romantic work that probably smuggles its beliefs past casual readers.
Hesse’s real challenge to readers is to show them that, whatever life they are living, they are more like Govinda than Siddhartha.