Class summary 9/14

* Three ways to make people rich or get more income:

                 1. produce more product so they can use more

                                      2. trade between both for each others' benefits (symbiosis)

                                               3. have family taken care of you so that you do not need to        spend you income on basic things 

* 15% of products we are using today on the earth are actually produced, the rests are naturally existed.

* intensive growth & extensive growth