Often on Chowhound I see posts asking questions like "What's the difference between bleached an unbleached flour?" or "How do I get my vegetables to keep their color when I cook them?" I personally was plagued with a cookie problem -- my cookies were coming out too tough, too crumbly not chewy like the cookies of my childhood. So I bought Cookwise by Shirley Corriher. It has the answers to all those questions, and the scientific reasoning behind them, only you can understand the explanations. I found out that Northern brands of flour (I've been using Hecker's) have a higher protein than national brands, and therefore create tougher cookies. I haven't actually tried any of the recipes, but it's a great cookbook just to read and discover why a recipe is good or not (Oh -- sugar keeps bread from rising properly. That's why that bread came out so dense) I know I sound like a shill, but this book totally opened my eyes to a whole new aspect of cooking.