30 Phil, Chapter 10: Pyrrho of Elis and Skepticism  
Pyrrho, the skeptic, believed no one knows anything. Everything can be questioned. The best approach is to keep an open mind. Like Socrates, Pyrrho himself left no writings. We know of his teachings through his students and later writers. 

Phrases that best represent skeptics:

• Question everything.
• Do not trust your senses.
• What difference does it make if you are alive or dead?

There’s a big difference between a pure skeptic questioning literally everything, and a moderate skeptic who evaluates everything with an open mind. Pyrrho is reported to have been a pure skeptic, I’m more of a moderate skeptic.