John 3:14

And as Moses, &c.--Here now we have the "heavenly things," as before the "earthly," but under a veil, for the reason mentioned in Joh 3:12. The crucifixion of Messiah is twice after this veiled under the same lively term--"uplifting," Joh 8:28; Joh 12:32-33. Here it is still further veiled--though to us who know what it means, rendered vastly more instructive--by reference to the brazen serpent. The venom of the fiery serpents, shooting through the veins of the rebellious Israelites, was spreading death through the camp--lively emblem of the perishing condition of men by reason of sin. In both cases the remedy was divinely provided. In both the way of cure strikingly resembled that of the disease. Stung by serpents, by a serpent they are healed. By "fiery serpents" bitten--serpents, probably, with skin spotted fiery red [KURTZ]--the instrument of cure is a serpent of brass or copper, having at a distance the same appearance. So in redemption, as by man came death, by Man also comes life--Man, too, "in the likeness of sinful flesh" (Rom 8:3), differing in nothing outward and apparent from those who, pervaded by the poison of the serpent, were ready to perish.

— Jamieson-Fausset-Brown Commentary (public domain)