There are two types of people in the world. Those who divide the world into two types of people, and those who don’t.
No idea where this quotation came from, but I always think of it whenever I come across black and white classifications in psychology.
Alternatively, McSweeney’s has a typology based on breakfast cereal.
Mind Hacks 
I first heard it from Felipe Fernandez-Armesto, who quotes and acknowledges it in his book Civilizations, which I don’t have to hand. Sorry.