Deci and Ryan say motivation is sourced from relatedness, competency, and autonomy. Don't have a citation, sorry.
The more I think on it, the more I like Yegge's book, A Basic Guide for Valuing a Company. Which means I should check out the other book that he has out that PSU doesn't have, Self-Defense Finance: For Small Businesses. Now I just need to find a macroeconomics textbook that studies the rise and falls of countries in the same manner. ;)