To a God Unknown is a novel by John Steinbeck, first published in 1933. The book was Steinbeck's second novel (after his unsuccessful Cup of Gold), the title taken from a hymn excerpt of the Rig Veda's Book X. Steinbeck found To a God Unknown extremely difficult to write; taking him roughly five years to complete, the novella proved more time-consuming than either East of Eden or The Grapes of Wrath, Steinbeck's longest novels.
After receiving a blessing from his dying father, Joseph moves to central California and settles in a valley near a town called Nuestra Señora. Shortly after beginning to build his homestead, he receives a letter from one of his brothers that their father had died, and in that moment Joseph feels that his father's soul enters the large oak tree by his homesite.
Joseph's three brothers subsequently move out to the valley with their families, and homestead the adjacent land. One day, the brothers come across a pine forest, and in the center is a quiet, circular glade with a stream flowing out of the large rock. Juanito, a ranch-hand, tells them that it is a sacred place to the indios.
Joseph then marries a school-teacher from Monterey named Elizabeth. Upon returning to the farm from the wedding, they find that the youngest brother, Benjy, an alcoholic, had been stabbed and killed by Juanito when he discovered him seducing his wife. When they meet later that night at the sacred rock, Juanito asks Joseph to kill him in revenge for his brother, but Joseph refuses. Joseph wants to pass it off as an accident, and for him to stay, but Juanito flees the farm.
For a time, the farm prospers, and Elizabeth bears a child. Joseph's brother, Burton, a devout Christian, becomes increasingly concerned with Joseph's late night 'talks' with the tree. The farm is then the site of a New Year's fiesta, and Burton decides to leave the farm after seeing the 'pagan' activities. After he leaves, the remaining brothers discover that Burton had girdled the tree to kill it. In the following rainless winter everything begins to die as a severe drought sets in.
One day, Joseph and Elizabeth visit the glade. Elizabeth decides to climb on the mossy rock, when she falls and breaks her neck, dying instantly. Soon thereafter, Joseph and Thomas decide to drive the cattle out to San Joaquin to find green pastures. At the last minute, Joseph decides to stay, then lives by the rock and watches the stream dry up. Juanito returns and convinces Joseph to visit the town's priest to enlist his help in breaking the drought. The priest refuses to pray for rain, saying that his concern is the salvation of human souls.
Joseph returns to the rock to find the stream dry. When trying to saddle his horse, he frightens the animal and receives a cut on the arm from a saddle buckle. Joseph then climbs to the top of the rock and slits his wrists. As he sacrifices himself to some mysterious higher power, he feels the rain begin falling down.
The novel examines what is meant by belief and how it affects different people. It also portrays the connection between the farmer and the land, a common theme, which appeared also in his later novels, such as East of Eden. It was one of Steinbeck's first books.