Oh, human being, know yourself

This is an ancient teaching. It is also as imporant a teaching as any that may exist:

I must first know myself, as the Delphian inscription says; to be curious about that which is not my concern, while I am still in ignorance of my own self, would be ridiculous. And therefore I bid farewell to all this; the common opinion is enough for me. For, as I was saying, I want to know not about this, but about myself: am I a monster more complicated and swollen with passion than the serpent Typho, or a creature of a gentler and simpler sort, to whom Nature has given a diviner and lowlier destiny?

-- Socrates