These first quotations are from The “Miscellanies” (Entry Nos. a-z, aa-zz, 1-500), ed. by Thomas A. Schafer, vol. 13 of The Works of Jonathan Edwards (New Haven, CN: Yale University Press, 1994).
"There has been much cry of late against saying one word, particularly about the Trinity, but what the Scripture has said; judging it impossible but that if we did, we should err in a thing so much above us. But if they call that which necessarily results from the putting [together] of reason and Scripture, though it has not been said in Scripture in express words—I say, if they call this what is not said in the Scripture, I am not afraid to say twenty things about the Trinity which the Scripture never said." (Works, 13, p. 256-57; Misc. no. 94).Here's another set of complementary notes from Jonathan Edwards, The “Miscellanies” (Entry Nos. 501-832), ed. by Ava Chamberlain, vol. 18 of The Works of Jonathan Edwards (New Haven, CN: Yale University Press, 2000). Jonathan Edwards makes the Trinitarian connection when he struggles with the end or purpose or goal of God’s creation. These are some of my favorites:
"God created the world for his Son, that he might prepare a spouse or bride for him to bestow his love upon; so that the mutual joys between this bride and bridegroom are the end of creation" (Works, 13, p. 372; Misc. no. 271).
"This spouse of the Son of God, the bride, the Lamb's wife, the completeness of him who filleth all in all, that for which all the universe was made. Heaven and earth were created that the Son of God might be complete in a spouse." (Misc. no. 103).
"God made all things, and the end for which all things were made, and for which they are disposed . . . is that God's glory may shine forth and be received (Works, 13, p. 496; Misc. no. 448).
“The end, the ultimate end of the creation of God was to provide a spouse for His Son, Jesus Christ, that might enjoy Him, and on whom He might pour forth His love. Heaven and earth were created in order that the Son of God might communicate His love to His spouse and bring that bride into the very family life of the Trinity" (Misc. no. 710).It really doesn't get much better than that. Personally, I don't think this is speculation at all. I believe Edwards is exactly right about the end or goal of creation. This is systematic theologizing at it's best, grounded in the story arc of the Bible as a whole.
“It seems by this to have been God’s design to admit man as it were to the inmost fellowship with the deity. There was, as it were, an eternal society or family in the Godhead, in the Trinity of persons. It seems to be God’s design to admit the church into the divine family as his Son’s wife” (Miscellanies, 741; vol. 18, p. 367).