Ya gotta love this piece from Alexander Pope's, "An essay on man." This little extract about knowing oneself is a classic.  
"Know, then, thyself, presume not God to scan; The proper study of mankind is man. Placed on this isthmus of a middle state, A being darkly wise, and rudely great: With too much knowledge for the skeptic side, With too much weakness for the stoic's pride, He hangs between; in doubt to act or rest; In doubt to deem himself a god, or beast; In doubt his mind or body to prefer; 'Born to die, and reasoning but to err; And alike in ignorance, his reason such, Whether he thinks too little, or too much; Chaos of thought and passion, all confused; Still by himself abused, or disabused; Created half to rise, and half to fall; Great lord of all things, yet a prey to all; Sole judge of truth, in endless error hurled."