As a Caravaggio lover, the Inspiration of St Matthew is one of my favorite's too. It's not just his dramatic use of light and darkness that I love, it's what he's doing with it to bring out the narrative. What is Caravaggio doing with his storytelling as he shows us Matthew looking not just startled but perhaps even a bit unwilling? Does the angel look bemused, or is that expression something else? What are they saying to each other?

I think Caravaggio'd masterful use of light draws us to these details and almost forces us to ask these questions.