Siddhartha, the handsome and quick-minded son of a Brahman, performs the rites, masters reflection and debate, and is loved by everyone, yet he finds no joy in himself. The teachings of his father and the wise men have filled his vessel without quieting his soul, and he begins to doubt that sacrifices and holy verses can ever reach the Atman, the innermost self. After standing motionless through a whole night until his father consents, he leaves home with his friend Govinda to join the Samanas, the wandering ascetics of the forest.
For about three years he fasts, endures heat and rain, and learns to slip out of his self into animals and stones, only to find that every exercise ends where it began. Meditation, he decides, is just a short flight from the self, the same numbing a drinker buys with rice-wine. When the friends seek out Gotama, the Buddha, Govinda takes refuge in his order, but Siddhartha, though he calls Gotama the one man before whom he must lower his gaze, departs: the teachings contain everything except the secret of what the Buddha himself experienced. He resolves to learn from himself, and the visible world returns to him in color, as if seen for the first time.
In the city he asks the beautiful courtesan Kamala to teach him love and the merchant Kamaswami to take him into trade. He arrives owning nothing but three arts, he can think, he can wait, he can fast, and for years he plays at business like a game while remaining a Samana at heart. Slowly the game wins. Riches, wine, and dice make his soul heavy and sick, until disgust drives him out of the city to a river, where he is ready to let himself drown. Out of a remote corner of his soul rises the holy syllable Om; he sleeps a deep, dreamless sleep beside the water and wakes renewed.
He stays at the river with Vasudeva, the old ferryman, learning the boat and, above all, learning to listen. The river shows him that time does not exist: it is at the source and at the mouth at once, and only the present is real. When Kamala dies of a snakebite while on pilgrimage to the dying Buddha, she leaves him the son he never knew he had. The pampered boy hates the ferrymen's poverty and patience and finally runs away, and Siddhartha learns the wound of helpless love, repeating the very grief he once inflicted on his own father.
One day, listening beside Vasudeva, he hears all the river's voices at once, and the thousand voices merge into the single word Om. His wound blossoms, his self flows into the oneness, and Vasudeva, his work done, walks into the forest. When the aged Govinda visits, still a searching monk, Siddhartha tells him that wisdom cannot be passed on, that the opposite of every truth is just as true, and that loving the world matters more than explaining it. Before they part, he has Govinda kiss his forehead, and the monk sees a flowing river of faces behind his friend's still face and bows before the same smile he once saw on the Buddha.