 The Greek word skepsis means investigation. Literally, a “skeptic” is an inquirer. Not all ancient philosophers whom in retrospect we call “skeptics” refer to themselves as such. Nevertheless, they all embrace ways of life that are devoted to inquiry. Ancient skepticism is as much concerned with belief as with knowledge. As long as knowledge has not been attained, the skeptics aim not to affirm anything. This gives rise to their most controversial ambition: a life without belief.