text: Sounds like a homework to me again. Was this asked by your professor? You should be doing your own reading but here is a helpful link that can get you started on:\nhttp://www.stoa.org/hopper/text.jsp?doc=Stoa:text:2003.01.0002:chapter=5\n\nEnjoy reading. If I were there and I really listened, I would probably get it on my own. Goodluck!