" At this point, the particles came in two types, called quarks—which rhymes with marks—and leptons. Quarks are quirky beasts. You’ll never catch a quark all by itself; it will always be clutching others nearby. I’m sure you have at least one friend or classmate who behaves similarly. Quarks are like those kids who never want to do anything alone, not even walk to the restroom. "

― Neil deGrasse Tyson , Astrophysics for Young People in a Hurry