There is no better example of this than the change in thinking among people regarding miasmas. Until this time, it had long been believed that miasma (polluted air) was the cause of disease. This shift in public belief shows how science and medicine can impact society. Therefore, this change in knowledge is the result of one of history's most significant contributions to science, the discovery of fermentation. Rosenberg identifies Pasteur's discovery as one of the key elements in the eventual identification and eradication of cholera. Rosenberg clearly describes the changes taking place in the scientific field, and from his writings it can be assumed that this is also the first introduction to the ontological theory of disease (external source of disease). Pasteur's fermentation experiments were taking place at the same time as the cholera epidemic and his results showed that spontaneous generation was not to blame but rather microscopic bacteria. Fungi as a source of disease in plants, animals and humans were already widely accepted. As a result, disease causation changed course and the foundation of germ theory was