To behold the Holy Trinity in Heaven, to behold that to which we ascribe the title of highest dogma of the Catholic Church, will be both the breaking point and fulfillment of our longing; our annihilation and our eternal minting.
Because our longing is eternal, words like “fulfillment” can seem mundane; yet fulfillment is exactly what the Holy Trinity partakes of, through its mere existence out of God’s love. Each Person of the Trinity partakes of each other in what is the non-dependent fulfillment of its own existence. The idea of our fulfillment has already been subsumed, thankfully, into what we cannot comprehend, and will not fully comprehend even in Heaven; though there will be full participation.
Our peace is, and can only be, the result of beholding the communion between the three Persons of the Trinity. What a revelation! Does God simply bestow His wand and say, “Now be fulfilled”? No, He opens out the revelation of His Own mystery, and grants to our own hearts through the Third Person of the Trinity, the revelation of His Son, the Second Person of the Trinity, Who in turn knows the Father, the First Person of the Trinity, and where the Son is there too is the Father. The perfect communion between the three Persons of the Trinity, beheld by a soul, consequently results in that soul's peace.
Our unity too must be the result of such beholding. For it is the very nature of the Trinity that to behold it is to want to seek the same unity in our relations with others. To those who are not in the state of mortal sin, and are in the state of sanctifying grace, the Holy Trinity is present within their own soul; and the love we give to our self must be the “self-love” of the Trinity, which births the desire to see ourselves in others, and further, to retain the image of the other within ourselves without altering it to our own image.