D: he discovered quarks.
He was very interested in Latin/Greek etymology early in life.
The idea of bound morphemes and prefix/suffix forms may have helped his insight.
After all, quarks are always hidden inside secondary particles like neutrons or protons.
I was reading the Discover mag on scientific genius recently.
It short-listed Fotini over at the Perimeter Institute, which I walk by every day on the way uptown, as a top-6 mind to crack "Grand Unified Theory".
I was supposed to have lunch with her a coupla times. But was never sure if that was intended as a diplomatic brush-off.
Anyway, her recent work suggests that spacetime is a secondary emergent property of a prior fundamental aspect of the universe.
The thinking would seem to be similar to what Gellman required.
Her folks are Greek, and she has an accent.
I wonder if a linguistic background growing up with agglutinative languages that use derivation helps with these sorts of scientific problems.