You've probably heard people mention the Enneagrams, Archetypes, Firo-B and NEO-PI, but do you know why? Do you know why they're popular, even among people who use the MBTI?

In this series, you'll find clear descriptions of what each of these ideas and instruments adds to the world of personality theory, and it turns out, they add a lot. There's never been a better time to be a student of personality, and you'll see why in these exciting issues.

"Where the MBTI culture encourages you to be 'true to your type,' the Enneagram culture states emphatically that your type is what stands between you and happiness, between you and perfection, between you and God."