One thing David DeAngelo mentioned in the Mastery Series was the Myers-Briggs typological approach to personality. It’s based off the findings of Carl Jung and allows one to understand not only themself better, but others, and how to interact with others. (Something I would have wanted to know last night when I ran into an overly drunk party girl from my school and I tried to ask her opinion on shit, should have just done kino and danced, though not take it any further as she was quite vulnerable).

I am an ISTP (Intoverted, Sensor, Thinker, Perceiver).

Here is an image detailing all 16 personality types.