The single theme of the novel is Siddhartha’s search for unity, which is identical with his search for the true nature of the self. He cannot find either by rejecting the world, but neither can he take the opposite route and indulge the senses. He must indeed embrace the world, but only when he is able to experience it sub specie aeternitatis, in its essential form. He must come to know that the individual self, the Atman, is identical to the universal self, the Brahman, although by the end of the novel the terms have shifted. He has, even while remaining an individual, become indistinguishable from the universal nature of the Buddha.