I came across this delightful quotation in J.C. Ryle’s work on John (volume 2, p. 145). Ryle is quoting Christopher Wordsworth, and Anglican bishop who wrote an entire Bible commentary:
God loves to effect His greatest works by means tending under ordinary circumstances to produce the very opposite of what is to be done. God walls the sea with sand. God clears the air with storms. God warms the earth with snow. So in the world of grace. He brings water in the desert, not from the soft earth, but the flinty rock. He heals the sting of the serpent of fire by the serpent of brass. He overthrows the wall of Jericho by ram’s horns. He slays a thousand men with the jawbone of an ass. He cures salt water with salt. He fells the giant with a sling and stone. And thus does the Son of God work in the Gospel. He cures the blind man by that which seemed likely to increase his blindness, by anointing his eyes with clay. He exalts us to heaven by the stumbling block of the cross.
God always seems to use the foolish things of the world to shame the wise, doesn’t He?