Tea is an addiction, but an addiction different from all others. It is milder, a habit relatively easily broken. It is more universal. Most unusually, it is good for the addict. And it is largely unnoticed both to those addicted and others. Indeed, the conquest of the world by tea has been so successfull that we have forgotten that it has happened at all. Tea has become like water or air, something that many of us take for granted. Alan Macfarlane, "The empire of tea"