Great article about permaculture. I have always had a deep interest in farming, and I remember first hearing about Polyface Farms in the book, The Omnivore's Dilemma. Since I read that book, it has influenced how I grow my own food in my backyard quite dramatically. While I cannot (in my limited space) stack systems on top of each other (such as cattle followed by mobile chicken coops), I do endeavor to do as much as I can. Great piece.