The authors of the Hippocratic Corpus did not avoid discussing diseases that are nowadays considered to be infectious. Yet, the notion of disease transmission from the unhealthy to the healthy laid beyond their perception. Galen refutes the possibility of transmission, as opposed to Diodorus, who underlines the contagious character of the 396 B.C. pestilence, and Titus Livius, a supporter of the notion of contagion, who provides us with an interesting testimony of the 212 B.C. plague. However, it is very interesting that a historian, Thucydides, is the first to mention the transmission of a disease from one person or country to another. In a way, his narration reflects his contemporary popular views on the matter. In the Latin, non-medical literature it is not difficult to be located references to the idea of contagion. In veterinary works in particular the idea of contagion, as a way of disease transmission, is quite apparent. Aretaeus must be the first physician to ever adopt a positive stance on contagion. All the above observations lead to the conclusion that historians, philosophers and zoologists do not refute the possibility of disease transmission through contagion, whereas physicians reject the idea, as it jeopardized their “rationalistic” theories about the cause of diseases.