A fascinating quote from Chrysostom on why Jesus may have used His own saliva to make the mud for the blind man’s eyes in John 9. Chrysostom doesn’t elaborate beyond this, but he’s on to something here: the Word is what goes out from the mouth of the Lord. Scripture several times uses that way of describing God’s Word in order to picture for us its efficacy and power. If it comes directly from God’s mouth, if it is breathed out by Him, then it cannot fail to be effective. It is a potent, life-giving, always-working Word. So just as the Word goes out from the mouth of the Lord to cure spiritual blindness, so here the Lord Jesus sends out His spit onto the ground as a means of healing the man’s physical blindness. There’s more beneath the surface of Scripture than we realize at times.
Also the fact that Jesus used spit and dirt to cure blindness is a wonderful reminder that He truly was man. He had a physical body that inhabited space and time in this world, while at the same time He had the power to cure blindness simply by wishing to do so — and it was done. Thus He is the God-man, both completely ordinary and extraordinary at the same time.
And why used He not water instead of spittle for the clay? He was about to send the man to Siloam: in order therefore that nothing might be ascribed to the fountain, but that thou mightest learn that the power proceeding from His mouth, the same both formed and opened the man’s eyes, He “spat on the ground”; this at least the Evangelist signified, when he said, “And made clay of the spittle.” Then, that the successful issue might not seem to be of the earth, He bade him wash. (St. John Chrysostom, Homily on the Gospel of St. John)