As a comment to Naming Infinity: A True Story of Religious Mysticism and Mathematical Creativity, a book by Loren Graham and Jean-Michel Kantor, I post this image “Vespers” by John Singer Sargent.
I love it for the expression of a specific concentration of mind which could be read as mystical — or mathematical, if one inclined so. What is the difference, after all? This is a common facial expression of a person in communication with the deepest level of his subconsciousness. Sargent painted “Vespers” in an Orthodox monastery at Corfu, but I have seen the same faces, in the same kind of mediterranean light, say, at Luminy.
The painting is in a museum in Liverpool, I can attest that the original is much subtler than any reproduction.