Every modern medical university student knows that asepsis is a system of measures aimed at preventing microorganisms from getting into the wound, and antisepsis is the fight against them. But this was not always the case, and until A. Leeuwenhoek discovered microorganisms using optical lenses, mankind could only guess about the existence of the smallest pathogens invisible to the eye. One day, exploring a drop of rainwater, which stood in a jug for some time, Leeuwenhoek found surprisingly small, but living "animals" that had different shapes and made random movements. The self-taught scientist gave them a detailed description, and the minds of modern times are still trying to understand how he managed to do this with such a small magnification. But however that might be, in 1683, bacteria were first discovered and later described. Prior to this, for many centuries, not only mankind had no protection against infections, but did not even recognize them as a disease at all. It was believed that they were "God's punishment for sins." The only advantage was that they tried to isolate such patients. Physicians of that time rightly noted that isolation prevents the spread of the disease. At his time, the Italian doctor Girolamo Fracastoro first suggested that the disease is transmitted from a sick person to a healthy through objects and can spread over a distance.