Genome analysis and the culture of human tissue are only two techniques that influence the reality of modern medicine at the beginning of the third millennium. The potentialities of medicine have for a long time ranged from before the beginning of life and can in parts remarkably prolong human life's ending. Medical progress has proved an uninterrupted dynamic for more than 100 years, inseparately connected with the general development of scientific and technical knowledge. The decisive presupposition of medical development is the introduction of natural science in the 19^th century. It is the starting point of medical development from a therapeutics which was mainly based on traditional concepts such as humoral pathology to a kind of medicine which is influenced by natural science and technology, soon to discover and heal causal connections between different pathological structures and mechanisms of the human organism. An example frequently quoted of this progress represents the enormous reduction of infectious diseases on the basis of the development of efficient vaccines and hygienic precautions. Rudolf Virchow, the founder of cellular pathology, belonged to the pioneers of modern medicine. He considered himself a natural scientist and defined the laboratory and the experiment as the genuine fields of activity of a physician.