St. Gregory the Pope
What signifieth it that God, the Maker of all, in this healing of the man, did put his fingers into the ears of the afflicted one, and did spit, and touch his tongue with the spittle?
What signifieth it also that he spat and touched his tongue? We receive somewhat out of the Redeemer's mouth upon our tongues when we receive wisdom to speak God's truth. Spittle is a secretion of the head which floweth into the mouth. And so it is that Wisdom, which is himself, the great Head of his Church, as soon as it hath touched our tongue, doth straightway take the form of preaching. And looking up to heaven, he sighed: not that he had any need to sigh unto his Father, for this same gave him whatsoever he asked: but he was fain to teach us to look up and sigh toward him whose throne is in heaven, thus confessing our need that our ears should be opened by the gift of the Holy Spirit, and our tongue loosed by the gift from our Saviour's mouth, (that, is, by knowledge of his divine word,) before we can use it to preach to others.
And he said unto him: Ephphatha, that is, Be opened. And straightway his ears were opened, and the string of his tongue was loosed. Herein we must remark that the command: Be opened: was addressed to the deaf ears, but that the dumb tongue also was immediately loosed. Just so, when the ears of a man's heart have been opened to learn the obedience of faith, the string of his tongue also is thereupon loosed, that he may exhort others to do the good things which himself doeth. It is well added: And he spake plain. He only doth well preach obedience to others who hath himself first learnt to obey.