Addiction is one of the most problematic and controversial disorders in modern medicine. There is no consensus as to which addictions are to be classified as an illness or as to whether they are connected by a common pathological basis. This study of the history of the origins of the modern concept of addiction in Germany in the late 18th and early 19th century, based on opium and alcohol addictions, can help to clear up some of these difficulties. The principal elements of the modern concept of addiction were established around 1800 when a new body image became popular and physicians started to distinguish between subjective well-being and objective health. The history of addiction, the hidden illness, is also a study of the concept of illness in modern medicine.