Cheese has been around since before the written record. People made the first cheese around 4,000 years ago. The first cheese was most likely made from the milk of sheep and goats, later other animals were used including donkeys and zebras; cheese has even been made from soy beans. Nomads carried milk in pouches made from the stomach lining or bladder of animals. The heat, motion, and rennin from the stomach lining combined to produce cheese. Since then cheese has been a part of life, from the cheese state of Wisconsin to imported French blue-cheese. Cheese has changed both a lot and very little from the beginning from poisonous Gloucester cheese in 1820 and the umbrella handle "parmesan cheese" to the traditional blue-cheese to processed cheese. Perhaps the biggest influence on cheese was J. L. Kraft who patented a cheese processing method in 1916 and changed the way America consumed cheese. Over the years cheese has gone from what America eats when they run out of meat to a delicacy. The cheese market is divided into three main categories, natural, processed, and imitation. The total retail sales for 2001 approached 11.1 billion. No matter how you look at it, cheese is very important.