The scientific problem with the human being is that we can estimate how long a complete and perfect description of his body would be, but we are far from writing such a description. And while earlier decades could flatter themselves that they were coming close to it, today we are no longer certain that our new insights do not increase the length of the text faster than we are able to write it down. And even if we were making good progress towards an excellent systems description of the human body, the abstract description, the set of equations and strange symbol chains which science can deliver will be in hopeless contrast to the live man with whom we shake hands. The human being is the result of an automatic production process called natural growth, and the resulting product has a systems character in many respects: it has lines for the transportation of air and food and blood, and it has a nervous network for the storage, transportation and processing of information. For a good systems description of a human being we could not ignore the history of the individual nor the history of his ancestors. The hypothesis that so-called simple physical laws govern every event in the body may be the correct theory, but it tells us nothing about the body as a system. And, in fact, not only in the present state of physical science, but also in the foreseeable future the systems description of man will have to be highly imprecise. Once I coined a very simple sentence to illustrate this: what could the lover gain from the switching diagram of his fiancee? It could be argued that this is an unfair remark. But any operation of the computer is in fact a man/machine system and it cannot be made clear enough that this means a cooperation between a structure where the switching diagram is everything, and a structure where the switching diagram is not available, and if it were it would mean nothing.