Three times in the Gospels, Jesus heals with spit.
He puts his fingers in a deaf man's ears, then spits and touches his tongue (Mark 7:33). He spits on a blind man's eyes (Mark 8:23). He spits on the ground, makes mud, and puts it on the eyes of a man born blind (John 9:6). Strange?
But watch what happens next, and one word keeps showing up: "Ephphatha!" (which means "Be opened!"). This word appears 77 times in the New Testament.
Open Mounce's Complete Expository Dictionary of Old and New Testament Words, available with Bible Gateway Plus, to that word and here's what you find:
This word is most common in the NT in the writings of John (Revelation and the Gospel of John). It can simply mean "to open" but elsewhere has the connotation of healing. It can also mean "to reveal" or "to speak."
Later in the same entry, Mounce ties anoigō directly to the healings of Jesus:
Frequently anoigō depicts a miraculous event, such as the opening of eyes in restoration of sight (Mt 9:30; 20:33; Jn 9:10, 14, 17, 21, 26, 30; 10:21; 11:37), of ears to restore hearing (Mk 7:35), and of the mouth to restore speech (Lk 1:64). It is used of Jesus' divine ability to do such miracles: "Nobody has ever heard of opening the eyes of a man born blind" (Jn 9:32).
That's the key. The spit and the mud aren't the point. The opening is. And no one but Jesus could do it. The means were unexpected. The One doing the opening was unmistakable.