Relativity

If I were a cartoonist, I'd draw a cartoon with two old men sitting on a park bench, one being Albert Einstein, the other being either Plato or Thomas Hobbes (I don't know what either of them looked like or even if they lived long enough to be old, which is why this cartoon doesn't work without some explanation).

Plato (or Hobbes) would look at Einstein, and say, "So, you really think that everything is relative?"

To which Einstein would reply, "Absolutely!"