My favorite Avenger is the character called "The Vision." In the movie adaptation of the hit comic book series, the Vision was portrayed as being the possessor of the "mind stone", one of the Infinity gems that are the said to be the receptacles of all the power that is in the universe—and the object of Thanos' covetous inclinations. This makes the Vision very special indeed. But while he can do a lot of cool stuff—like alter his density to intangibility or diamond-hardness—this is not why I like him. I like him because he reminds me of John Owen's most important theological contribution (at least in reference to my own appreciation of it and its implications)—the doctrine of the beatific vision.
To be sure, John Owen was not the first to articulate this doctrine. It was the great Thomas Aquinas who gave prominence to the doctrine and Owen owes much of his thought on the subject to the former. However, Owen did in fact improve upon Aquinas' take on the BV. In a nutshell, Aquinas' notion of the BV consists in it being the human being's intellectual fruition as pertaining to the knowledge of God. As image-bearers, we have the capacity to know God and this knowing, maximally heightened as creaturely possible, will be our blessedness in glory. For Aquinas, the BV is still mediated by Christ through the Spirit.
While Owen does not particularly disagree with this, he extends, as it were, Aquinas' formulation and grounds the BV on Christ Himself as the object of this vision. When Aquinas seemingly gives Christ a utilitarian function in the BV, Owen makes Christ both the mediator and the essence of the BV. We behold God in the face of the God-Man, Jesus Christ. The saint's blessedness in glory, according to Owen, will be in marveling at and enjoying God's greatest work, the hypostatic union. And it gets better.
Francis Turretin, along with Aquinas, does not give the physical senses, even though glorified, any place in the BV, but Owen includes the physical sight of Christ as part of our blessedness. In other words, not only will we enjoy the divinity of Christ in heaven but His humanity as well.
In terms of the importance of the doctrine of the beatific vision for the Christian life this side of glory, Owen gives it the paramount place. He writes the ff. in "The Glory of Christ" (the last book he ever wrote):
No man shall ever behold the glory of Christ by sight hereafter, who does not in some measure behold it by faith here in this world. Grace is a necessary preparation for glory, and faith for sight. Where the subject (the soul) is not previously seasoned with grace and faith, it is not capable of glory or vision. Nay, persons not disposed hereby unto it cannot desire it, whatever they pretend; they only deceive their own souls in supposing that so they do. Most men will say with confidence, living and dying, that they desire to be with Christ, and to behold his glory; but they can give no reason why they should desire any such thing, -- only they think it somewhat that is better than to be in that evil condition which otherwise they must be cast into for ever, when they can be here no more. If a man pretend himself to be enamoured on, or greatly to desire, what he never saw, nor was ever represented unto him, he does but dote on his own imaginations. And the pretended desires of many to behold the glory of Christ in heaven, who have no view of it by faith whilst they are here in this world, are nothing but self-deceiving imaginations.
We behold Christ by faith now through the means of grace and we shall behold Him by sight immediately in glory thereafter.
Looking to Christ by faith is an outflow of Spirit-regenerated and Spirit-enflamed affections. If we hunger and thirst for Him now and love Him with all our heart, soul, mind, and strength, we shall surely be satisfied with being with Him and seeing Him face-to-face in glory for we have proven to be His friends while here on earth.
Click on the ff. for a very good lecture by Suzanne McDonald (contributor to The Ashgate Research Companion to John Owen's Theology, where she discusses the BV) on Owen's doctrine of the beatific vision: "Beholding God's Glory: John Owen and the 'Reforming' of the Beatific Vision"
Click on the ff. for quotes that can be used a devotional aids from Owen's "The Glory of Christ": Highlights of John Owen's "The Glory of Christ"