>>16905108The last supper by Leonardo Da Vinci.
I believe what you are seeing is an x-ray showing all the layers of paint. The technique he used was a really tricky one to pull off. You basically mix pigment with plaster, a substance that dries quick. This requires you to paint really fast and precise. There's probably a bunch of failed atempts and sketches underneath the one we know.
Here you're seeing them all at once.
