I would agree that Maxwell belongs above Feynman if we're talking about modern physicists and not limiting ourselves to the 20th century. What really amazes me

I would agree that Maxwell belongs above Feynman if we're talking about modern physicists and not limiting ourselves to the 20th century. What really amazes me is that Maxwell got as far as he did with the incredibly clunky notation he was using. Our modern notation, IIRC, is due to Heaviside, and was a huge improvement.