When you find the area of overlap between purpose, passion, and talent, the need area tends to be fairly easy to fulfill. The first three areas will suggest potential careers. Here’s another way of thinking about it:
Need = what you must do
Talent = what you can do
Passion = what you love to do
Purpose = what you should do
This is a great entry, it sums up some many great things I have been trying to say and he does it really well.