it is highly significant that although the Tetragrammaton is made up of four letters and is therefore a quaternity, one of the letters duplicates itself and therefore the issue of the three and the four appears.
Edinger argues that the Kabbalistic structure of the Tetragrammaton enacts the three-and-four problem of individuation, with the doubled feminine letter revealing the undifferentiated status of the anima in masculine symbolic systems.
, The Mysterium Lectures: A Journey Through C.G. Jung’s Mysterium Coniunctionis, 1995thesis