Cardinal Joseph Ratzinger (later Pope Benedict XVI) in "Salt of the Earth" saw this practice as based on Jesus' words in : "Some are eunuchs because they were born that way; others were made that way by men; and others have renounced marriage because of the kingdom of heaven. The one who can accept this should accept it." He linked this celibacy "because of the kingdom of heaven" with God's choice to confer the Old Testament priesthood on a specific tribe, that of Levi, which unlike the other tribes received no land from God, but which had "God himself as its inheritance" ().