Above the gates at Delphi, a short inscription greeted every weary traveler: This simple advice was considered the most important piece of knowledge anyone could possess. And to understand what the oracle told you, you first had to understand yourself. There is good reason for this: if we do not know our own mind, our dreams, strengths and failings, how can we reach the heights we seek? We become like a ship with no rudder. Which is why knowing yourself is so important: it helps you make decisions that make you happier, because you end up pursuing goals that are true to your very nature and core.