Robert Benchley once wrote that there are two kinds of people in the world: those who believe that there are two kinds of people in the world, and those who do not.
Jim Svejda, a colleague in graduate school divided people into bunchers and folders. Jonathan Swift suggested that we could be either fools or knaves. There are creationists and evolutionists, early risers and night owls, Whigs and Tories, Guelphs and Ghibelenes, the quick and the dead.
Today is my birthday, and, feeling, frivolous, I’m inviting you to comment by adding to the categories of the two classes of people. I’ve given you a start; now you’re on your own.