Are there books describing the general principles of cooking?
The best resource for this kind of questions is On Food and Cooking: The Science And Lore Of The Kitchen, by Harold McGee. It's best described as 'a cookbook without recipes', even though there are a couple of them in there.

It has several sections and describes in detail what various foodstuffs contain and how they are affected by different cooking methods. For example, there's a chapter on Bread, which goes through the whole process from kneading the dough to the crumb going stale.

It's very thorough, but also very readable. (I have read both the 1984 and 2004 editions cover-to-cover, and I don't think I'm the only one...)