From God in the Dock: Essays on Theology and Ethics:
"...modern people have an almost aesthetic dislike of miracles. Admitting that God can, they doubt if He would. To violate the laws He Himself has imposed on His creation seems to them arbitrary, clumsy, a theatrical device only fit to impress savages..."
Lewis pushes against this caricature of miracles and argues that Christ does here in miracles what God the Father does all the time. He quotes Jesus "The Son can do nothing of Himself, but what He seeth the Father do."
He continues, "There is an activity of God displayed throughout creation, a wholesale activity let us say which men refuse to recognized. The miracles done by God incarnate, living as a man in Palestine, perform the very same things as this wholesale activity, but at a different speed and on a smaller scale...some of the miracles do locally what God has already done universally: others do locally what He has not yet done, but will do."
Here's a few examples of what Lewis means.
"God creates the vine and teaches it to draw up water by its roots and, with the aid of the sun, to turn that water into a juice which will ferment and take on certain qualities. Thus every year, from Noah's time till ours, God turns water into wine. That, men fail to see...But when Christ at Cana makes water into wine, the mask is off. The miracle has only half its effect if it only convinces us that Christ is God: it will have its full effect if whenever we see a vineyard or drink a glass of wine we remember that here works He who sat at the wedding party in Cana."
Or, "The miracles of healing fall into the same pattern. This is sometimes obscured for us by the somewhat magical view we tend to take of ordinary medicine. The doctors themselves do not take this view. The magic is not in the medicine but int he patient's body. What the doctor does is to stimulate Nature's functions in the body, or the remove hindrances. IN a sense, though we speak for convenience of healing a cut, every cut heals itself; no dressing will make skin grow over a cut on a corpse...All who are cured are cured by Him, the healer within. But once He did it visibly, a Man meeting a man. Where He does not not work within in this mode, the organism dies. Hence Christ's one miracle of destruction is also in harmony with God's wholesale activity. His bodily hand held out in symbolic wrath blasted a single fig tree, but no tree died that year in Palestine, or any year, or in any land, or even ever will, save because He has done something, or (more likely) ceased to do something."
Lewis argues the same pattern is evident in the Virgin birth. God's normal way of making a man is through a man fertilizing a woman. "What he did once without a human father, He does always even when He uses a human father as His instrument."
This leads Lewis to conclude, rightly, that the miracles of the Bible aren't clumsy or arbitrary. They are not like the silly miracles in mythology. Instead, "the true miracles express not simply a god, but God: that which is outside Nature, not as a foreigner, but as her sovereign. They announce not merely that a King has visited our town, but that it is the King, our King."
I love Lewis.