Quarkways to particle symmetry

WHEN THE EDITORS OF PHYSICS TODAY asked me—or, better, challenged me—to write an article explaining unitary particle symmetries to physicists who are not fundamental‐particle specialists, I hesitated. But on considering the physicist whose children may ask, “Daddy, what are fundamental particles made of?”, I decided to write the article after all. That question—so innocent, so clear, so full of healthy curiosity—deserves to be answered, as far as possible, on the same level.