Tri-unity

And that passage in Gregory of Nazianzus vastly delights me: "I cannot think on the one without quickly being encircled by the splendor of the three; nor can I discern the three without being straightway carried back to the one." Let us not, then, be led to imagine a trinity of persons that keeps our thoughts distracted and does not at once lead them back to that unity. Indeed, the words "Father", "Son", and "Spirit" imply a real distinction--let no one think that these titles, whereby God is variously designated from his works, are empty--but a distinction, not a division.

John Calvin, Institutes 1.13.17