Most people have heard of Socrates, though not so many realize that we only know of him through the writings of his students, primarily Plato. Born sometime around 470 BC, Socrates is a foundational figure in the Western philosophical tradition and arguably the first moral philosopher in the West. He's kind of a big deal. Socrates was known to be a philosophical trickster, encountering people on the streets and asking them series of questions in a kind of "cooperative argumentative dialogue" aimed at negotiating and moving closer to truth.
Socrates famously said, "I only know, I know nothing." In these six words, he wisely contradicted perhaps every human who had ever lived (certainly the majority), asserting that he did not know the absolute truth of anything under the sun. This skepticism formed the basis of the Western philosophical and scientific traditions that profoundly shaped the world we see around us today. These six words are an ideal reminder to question all the things, believe nothing absolutely, acknowledge ambiguity, and preserve what Einstein called a "holy curiosity." The paradox, of course, is that knowing nothing in absolute terms is no excuse to stop learning.