And the nursing child shall play over the hole of the asp, and the weaned child shall put his hand on the adder's den.
Read Chapter 11
Ambrose of Milan
Hear how the antidote was administered to the flesh: the Word of God became flesh, put his hand into the serpent’s den, removed the venom and took away sin. In other words, “from sin, he condemned sin in the flesh.” - "Explanation of the Twelve Psalms 37.4"
Happily the Creator has promised by Isaiah to give this power even to little children, of putting their hand in the cockatrice den and on the hole of the young asps without at all receiving hurt. And, indeed, we are aware … that under the figure of scorpions and serpents are portended evil spirits, whose very prince is described by the name of serpent, dragon and every other most conspicuous beast in the power of the Creator. This power the Creator conferred first of all upon his Christ, even as the ninetieth psalm says to him: “Upon the asp and the basilisk shall you tread; the lion and the dragon shall you trample under foot.” So also Isaiah: “In that day the Lord God shall draw his sacred, great and strong sword” (even his Christ) “against that dragon, that great and tortuous serpent; and he shall slay him in that day.” - "Against Marcion 4.24"