Philosophers’ stone. In alchemy, a metaphor for the successful transmutation of base metal into gold; psychologically, an archetypal image of wholeness. (See also coniunctio.)
Jung quoted from the Rosarium philosophorum:
Make a round circle of man and woman, extract therefrom a quadrangle and from it a triangle. Make the circle round, and you will have the Philosophers’ Stone.[“Psychology and Religion,”CW11, par. 92.]