These are the 2 branches of economics
-Adam smith
Adam smith was one of the best economist from america, he wrote a book in which he said, (this is made up by me, i don't know if what is understood is completly correct) :"When an induvidual does not care about, by doing what he is providing to the society, is when an invisible hand makes him provide most to the society, perhaps not everytime."
Micro economics and macro
Production possibility curve