Madeleine F. Stebbins writes on St. Paul’s conversion:
At first it may seem odd to see Saul from this perspective, turned away from us, on his back. Also, why the prominence of the horse, which seems somewhat bewildered by what has happened? In the Psalms, the horse is symbolic of strength and power (c.f. 33:17;147:10). We say “riding on a high horse,” meaning in an attitude of pride. Jesus is never pictured on a horse, only on a donkey. But the young Saul, here in rich clothing, was in a state of complete self-assurance in his own righteousness, as well as of blind arrogance and fanatic zeal. So he had to be struck down from his horse.
Why this upside-down perspective of Saul? Because in an instant his world had been turned upside down. All he had lived for and was zealous for turned not only to ashes, but was seen in its truth as wicked. Conversion is depicted here as a total inversion, as a reverse, at antipodes with one’s perspective worldview.
A miracle of grace happens here, one of vast consequence for the history of Christianity. A shaft of “light from heaven” (Acts 9:3) causes instant blindness. Caravaggio gives this powerful sense of light in darkness, a glowing light that is mysterious, unfathomable and beautiful, like the light of eternity. He focuses with intense concentration on this intimate moment to the exclusion of all else. Saul is not reclining, as in other paintings on the subject, but utterly prostrate, shattered, humbled to the very ground, all his strength gone, his sword thrown down. Struck blind, he needed to undergo the death of the senses in order to see the new supernatural light. On the Feast of the Conversion of St. Paul, Pope Benedict said conversion is “always letting ourselves be formed by Christ; it is death and resurrection.”
I think that one of the strange-sounding consolations that being a Christian offers is the possibility of meeting death with a smile. Riffing off the last line above from Pope Benedict XVI, anyone who’s truly in relationship with Jesus Christ has at least one conversation moment. In my experience I have many, and somewhat often. (We convert because we naturally stray from goodness, because we’re creatures who sin.) It’s in undergoing many “little deaths” and resurrections of our souls that it seems possible actually to die with the Christian joy that so many great men and women have spoken of across time.