Sourdough is believed to have originated in Ancient Egyptian times around 1500 BC, and was likely the first form of leavening available to bakers. (UPDATE 05/29/2010: In order to avoid problems with mold, I've modified my recipe to follow the advise of Peter Reinhart (author of The Bread Baker's Apprentice) and recommend using pineapple juice the first two days of fermentation.) NOW, There are a few simple rules to follow when making your own sourdough starter. First, because it is a living organism, never use metal bowls, containers or spoons. When storing the starter, use only glass, crockery or plastic containters with a lid. The container size should be 3 times the volume of the ingredients (to allow expansion). Note: If the jar has a metal lid, poke a hole in the lid and put plastic wrap over the top of the containter. It's very important that it's 'home' be kept clean-- wash and sterilize the container periodically, and again, remember, no metal should ever touch the starter.