Glenn Gould's performing abilities are absolutely legendary, and rightfully so. But I've always found myself wondering why his analytical work is not more famous. Take these reflections on Beethoven's most famous sonatas, for example. You might not agree with them -- I think he's a bit too hard on old Ludwig, myself -- but they're fascinating (and thoughtful), all the same.
Attribution(s): "Glenn Gould" by Andrei P. via VisualHunt (CC BY-NC-SA).