My intention here is to discuss sources of strength for human beings, without wanting to sell anything or make a profit. What I write here is medical knowledge dating back to earlier and ancient times without having become anachronistic. We will talk about our organs and try to visualize them from an observer's standpoint. Our organs and how they function determines whether we are healthy or ill, and how we feel. It is they who give us a feeling of power or lack of it. In principle, it is always the human being as a living creature who receives strength they can draw upon, sometimes to the point of exhaustion. We need to discuss how this exhaustion comes about. What's important at the start, however, is that all of us are born with the power of youth, assuming that our development is not impaired by factors such as malnutrition, injury or genetic flaws. We are strong by nature; some of us are able to foster this strength from the outset and benefit from it even in old age. Others - unfortunately the majority - run out of it earlier. They develop diseases or at least ailments, and if these don't go away again so that exhaustion persists, the question arises as to how to regain strength. That is natural, because we want to be like "before". We again want to feel the strength which we consider proper and which nature intended for us.