Number, as it were, lies behind the psychic realm as a dynamic ordering principle, the primal element of which Jung called spirit. As an archetype, number becomes not only a psychic factor, but more generally, a world-structuring factor. In other words, numbers point to a background reality in which psyche and matter are no longer distinguishable.
"Psyche and Matter". Book by Marie-Louise von Franz, p. 2016, 1992.