If further inquiring into the characteristics of the aionion, still keeping its formal aspect rather than its substantial content in view, the first feature obtruding itself is that of the imperishableness, including the unchangeableness, of the things pertaining to it. Paul declares, almost after the manner of an axiomatic truth: “the things which are seen are temporal; but the things which are not seen are eternal,” 2 Cor. 4:17. At first this reads like a differentiating appraisal of the visible and the invisible, something reminding of the antithesis between the two worlds of the ideal and the sense-things with Plato. A closer examination of the words in their context will soon convince that this exegesis would convey only part of the meaning, and for the other part produce a wrong perspective. The emphasis does not rest on the seen versus the unseen, but on the fact that the former, under the present circumstances happens to consist of perishable things, whereas the other under the same circumstances possesses the nature of the eternal, of what from its very nature cannot perish, because it carries the principle of eternity in itself. A permissable paraphrase would be: the things that in this lower, preliminary, state engage our interest are transitory and corruptible; the things which in the present dispensation the believer cannot yet lay hold of by vision are the eternal, incorruptible realities. It goes without saying, that the distinction thus interpreted partakes not of the nature of a cool, disinterested diagnosis of metaphysical difference; there is a degree of pathos in the declaration, occurring s it does in a highly emotional context. Paul is conscious of σκοπευν “looking at,” that is contemplating with interest the makeup of the invisible world. Only,this mode of contemplation is with the Apostle not induced by the invisibleness of the things in question; in the abstract he practices no cult of the invisible as partaking per se of a superior complexion; that would be a Hellenic thought; but he has learned to recognize in the things unseen to the present aion the enduring things of the world to come, a world already in principle present, the contemplation of which can consequently render solace and support in the affliction of the moment. That thus and thus only the stress is rightly divided will be perceived from the closely following word: “for we pilgrimage through a land of faith, not of sight,” 2 Cor. 5:7. Here the unseen things of th either passage are precisely the things of future sight, deriving their spreme value from this prospective visibleness, whilst the walking through a region of faith is felt precisely as a matter of relative lack of importance.
—Geerhardus Vos, Pauline Eschatology, 191–92.