“‘And He stretched forth His hand, and touched him.’ (Matt. 8:3)
In the Law, the touch of the leper was contagious, but as there is such purity in Christ He absorbs all uncleanness and pollution, He does not contaminate Himself by touching the leper, nor does He transgress the Law.
For in assuming our flesh, He has granted us more than the touch of His hand. He has brought Himself into one and the same body with us in order that we should be the flesh of His flesh.
He does not only stretch out His arm to us, but He comes down from heaven, even to the very depths. Yet He catches no stain thereby, but stays whole, clears all our dirt away, and pours upon us His own holiness.
Now, while He could heal the leper by His word alone, He adds the contact of His hand to show His feeling of compassion: no wonder, since He willed to put on our flesh in order that He might cleanse us from all our sins.
So the reaching out of His hand was a sign and a token of His vast grace and goodness.
Here is a thing which we pass over without much impression at an idle reading, but must certainly ponder, with much awe, when we take it properly—that the Son of God, so far from abhorring contact with the leper, actually stretched out His hand to touch his uncleanness.”
–John Calvin, A Harmony of the Gospels: Matthew, Mark and Luke, Vol. 1; trans. A.W. Morrison, Ed. David Torrance and Thomas Torrance (Grand Rapids, MI: Eerdmans, 1972/1994), 1: 244. Calvin is commenting on Matt. 8:3; Mark 1:41; and Luke 5:13.