John 5:4

4.For an angel went down. It was, no doubt, a work peculiar to God to cure the sick; but, as He was accustomed to employ the ministration and agency of angels, so He commanded an angel to perform this duty. For this reason the angels are called principalities or powers, (Colossians 1:16;) not that God gives up his power to them, and remains unemployed in heaven, but because, by acting powerfully in them, he magnificently shows and displays his power. It is, therefore, wicked and shameful to imagine any thing as belonging to the angels, or to constitute them the medium of communication between us and God, so as to obscure the glory of God, as if it were at a great distance from us, while, on the contrary, he employs them as the manifestations of his presence. We ought to guard against the foolish speculations of Plato, for the distance between us and God is too great to allow us to go to the angels, that they may obtain favor for us; but, on the contrary, we ought to come direct to Christ, that, by his guidance, protection, and command, we may have the angels as assistants and ministers of our salvation.

At intervals. God might have at once, in a single moment, cured them all:, but, as his miracles have their design, so they ought also to have their limit; as Christ also reminds them that, though there were so many that died in the time of Elisha, not more than one child was raised from the dead, (2 Kings 4:32;) (95) and that, though so many widows were famished during the time of drought, there was but one whose poverty was relieved by Elijah, (1 Kings 17:9; Luke 4:25.) Thus the Lord reckoned it enough to give a demonstration of his presence in the case of a few diseased persons. But the manner of curing, which is here described, shows plainly enough that nothing is more unreasonable than that men should subject the works of God to their own judgment; for pray, what assistance or relief could be expected from troubled water ? But in this manner, by depriving us of our own senses, the Lord accustoms us to the obedience of faith. We too eagerly follow what pleases our reason, though contrary to the word of God; and, therefore, in order to render us more obedient to him, he often presents to us those things which contradict our reason. Then only do we show our submissive obedience, when we shut our eyes, and follow the plain word, though our own opinion be that what we are doing will be of no avail. We have an instance of this kind in Naaman a Syrian, whom the prophet sends to Jordan, that he may be cured of his leprosy, (2 Kings 5:10.) At first, no doubt, he despises it as a piece of mockery, but afterwards he comes actually to perceive that, while God acts contrary to human reason, he never mocks or disappoints us.

And troubled the water Yet the troubling of the water was a manifest proof that God freely uses the elements according to his own pleasure, and that He claims for himself the result of the work. For it is an exceedingly common fault to ascribe to creatures what belongs to God alone; but it would be the height of folly to seek, in the troubled water, the cause of the cure. He therefore holds out the outward symbol in such a manner that, by looking at the symbol, the diseased persons may be constrained to raise their eyes to Him who alone is the Author of grace.