John Chrysostom — as excerpted in the Catena Aurea on John 9:1-7

“(Hom. lvi. 2) He then confirms His words by deeds: When He had thus spoken, He spat on the ground, and made clay of the spittle, and anointed the eyes of the blind man with the clay. He who had brought greater substances into being out of nothing, could much more have given sight without the use of any material: but He wished to shew that He was the Creator, Who in the beginning used clay for the formation of man. (Hom. lvii. 1). He makes the clay with spittle, and not with water, to make it evident that it was not the pool of Siloam, whither He was about to send him, but the virtue proceeding from His mouth, which restored the man’s sight. And then, that the cure might not seem to be the effect of the clay, He ordered the man to wash: And He said unto him, Go, wash in the pool of Siloam. The Evangelist gives the meaning of Siloam, which is by interpretation, Sent, to intimate that it was Christ’s power that cured him even there. As the Apostle says of the rock in the wilderness, that that Rock was Christ, (1 Cor. 10:14) so Siloam had a spiritual character: the sudden rise of its water being a silent figure of Christ’s unexpected manifestation in the flesh. But why did He not tell him to wash immediately, instead of sending him to Siloam? That the obstinacy of the Jews might be overcome, when they saw him going there with the clay on his eyes. Besides which, it proved that He was not averse to the Law, and the Old Testament. And there was no fear of the glory of the case being given to Siloam: as many had washed their eyes there, and received no such benefit. And to shew the faith of the blind man, who made no opposition, never argued with himself, that it was the quality of clay rather to darken, than give light, that He had often washed in Siloam, and had never been benefited; that if our Lord had the power, He might have cured him by His word; but simply obeyed: he went his way therefore, and washed, and came seeing. (Hom. lvi. 2). Thus our Lord manifested His glory: and no small glory it was, to be proved the Creator of the world, as He was proved to be by this miracle. For on the principle that the greater contains the less, this act of creation included in it every other. Man is the most honourable of all creatures; the eye the most honourable member of man, directing the movements, and giving him sight. The eye is to the body, what the sun is to the universe; and therefore it is placed aloft, as it were, upon a royal eminence.”