The first thing I learned in pre-school was how to recycle. (The second thing I learned was how not to bite my cubby-mate.) We separated glass bottles from plastic, sorting them into their appropriate containers. Before long, I was reducing, reusing, and recycling like a champ. But what I didn’t know was that each time I tossed a crusty milk carton into those bright blue bins, I was recalling a practice that is over two millennia old.