When visiting the Norton Simon Museum in Los Angeles two weeks ago, I was enthralled with the x-ray pictures the museum posted of various artworks.
Here's a picture of the x-ray of van Gogh's painting titled "Winter - The Vicarage Garden under snow". This x-ray shows a painting van Gogh did and for whatever reason, he chose to paint over it. I have many artist friends who do this too, but seeing this master's real x-ray made me kind of giddy... More proof to share with my students that everyone creates art they're unsure of - the goal is not to let it deter you. Just like van Gogh didn't! The x-ray above shows the painting that exists "under" the painting below. More info. about the painting here.