John Polkinghorne on Quarks

"Quarks are unseen realities. No one has ever seen or isolated a single quark in the lab. So we believe in them, not because, even with sophisticated equipment, we have seen them, but because assuming they are there makes sense of great swathes of physical experience."

-- John Polkinghorne is a British particle physicist, an anglican priest, a winner of the Templeton Prize, and a knight of the British Empire.