Hold on. Here we go.
Edwards surmised that if an eternal and divine being existed then that eternal and divine being must not only be perfect, but must also love, adore, and exult in perfection. So, there must be some sort of duplicity in the make-up of this divinity.
However, the reciprocity and reflexivity of that being loving itself could not be fully expressed or experienced with mere duality. The mutual nature of its personal adoration would be too linear and merely mutual. But what if there was more than a duplicity in this divine being? What if there was a Tri-Unity in this being?
If a divine and eternal being exists, posits Edwards, then it must exist in a plurality of three. Its subsistence cannot be two, yet one - this would not accomplish its innate purposes [to love and adore perfection perfectly]. And its subsistence cannot be four, yet one - this quadality would be superfluous to its purposes.
Pretty fun, eh? I told this to one of my students today and they got it! I did have a board to draw on. Perhaps I just felt that after posting that video, I had to post something that stretched the brain a bit. It stretched mine to write it.
"To the only God our Savior, through Jesus Christ our Lord, be glory, majesty, dominion, and authority before all time and now and forever. Amen." [Jude 25]