A zetetic person is a skeptic — they are doubtful of everything and want to explore the evidence before proceeding. The word “zetetic” comes from the Greek “zetetikos,” meaning “searching, inquiring.” On the extreme fringes, zetetic astronomy operates on the belief that the Earth is on a flat plane and the sun, moon, and other bodies in the sky are only a few thousand feet above it. But true zetetic thinkers have disproved this theory through vigorous inquiry — Aristotle was the first scholar to notice round shadows being cast during a lunar eclipse, and centuries of astronomers have disproved the flat-Earth theory.