According to the theory of scalar diffraction, first, the equipollence of spatial distribution of the plane-wave interferential field and parallel projective sine grating is discussed.
The Thinking Mind Podcast: Psychiatry & Psychotherapy
I mean, one of the important theories, I think, in couple psychoanalysis or psychotherapy is the idea of a couple projective system, meaning that each partner is projecting split off parts of themselves into the other.
You could make this sensible with the notion of projective geometry, which takes seriously the idea of points at infinity, but for our purposes, think of three circles that don't intersect and don't have the same size.