Since it's Lent, I'll draw your attention to a wonderful article on Raphael's Crucifixion and the Mass by David Clayton, featured on New Liturgical Movement: http://www.newliturgicalmovement.org/2012/03/mass-portrayed-in-raphaels-crucifixion.html
The only thing I have to add is what one of my priests mentioned recently in a lecture about the Tridentine Mass. There are 3 spiritual levels to this painting, which recalls the 3 steps the priest ascends to the altar
My apologies for lack of posts lately. I'm about to have a baby any day now so I've been conserving my energy and activities. I have managed to complete one sample illustration to be submitted to publishers with a friend's manuscript for a children's book on the Parables. Hopefully I'll be able to post it in the future.