The four postulates of Robert Koch.

A critical revision of the "Four postulates of Koch". The erroneousness of the 3rd and 4th postulates are justified in an historical perspective. Koch could not foresee the future progress of medicine and microbiology, but he could have imagined it; imagination is an endowment of scientific thinking. Koch considered science as a static and incontrovertible activity, but did not foresee the future development of that technological progress that soon after allowed to "see" the viruses and greatly widened the concept of infection.