The Three Pure Ones, Sanqing, are the highest deities of religious Daoism, the personified forms of the Dao itself and the source from which all other gods are held to derive. They are the Celestial Worthy of Primordial Beginning (Yuanshi Tianzun), the Celestial Worthy of Numinous Treasure (Lingbao Tianzun), and the Celestial Worthy of the Way and its Virtue (Daode Tianzun), and each is said to dwell in one of three pure heavens or realms at the summit of the Daoist cosmos. They represent, in the developed theology, the successive unfolding of the ineffable Dao into manifestation, the primordial origin, the sacred treasure or scripture that transmits it, and its expression in the world, so that the three together are less three separate gods than three aspects of a single ultimate reality. The Sanqing as a unified triad is itself the product of harmonizing originally separate scriptural revelations.
The Shangqing ("Upper Clarity") scriptures originated in visions received by the medium Yang Xi beginning in 364 CE, later transmitted to Mount Maoshan and expanded there by Tao Hongjing, founder of the Maoshan school; the Lingbao ("Numinous Treasure") scriptures, from which Lingbao Tianzun draws his name, developed as a related but separate revealed corpus in the following generations, incorporating Buddhist as well as earlier Daoist material. Bringing the deities associated with these traditions together with the Daode Tianzun of the older Laozi cult into one triad presiding over three heavens was a later systematizing move, so the apparently ancient Three Pure Ones scheme is in fact a synthesis of originally distinct lineages of revealed scripture.