For a while I've been noticing different versions of this symbol in various personality typing systems. What's interesting is how different systems use it for different things: Socionics for the quadras, Keirsey for the temperaments, etc. I don't know if this is a coincidence or if it's some sort of archetype, but I find it fascinating regardless. I don't know what this symbol is officially called (the closest I can find is "quartered circle"), so I've nicknamed it "The Magic Symbol."