Take a thorough case when investigating an epidemic or sporadic disease. With few exceptions, each reigning epidemic differs from all previous ones.
In the investigation of the symptom complex of epidemic or sporadic diseases, it makes no difference if something similar has ever appeared before under the same or any other name. The novelty or peculiarity of such a contagion makes no difference, either in its examination or its cure, since the physician presupposes that the pure image of each and every presently reigning disease is new and unknown. He must explore it for himself from the ground up if he wants to be a genuine, thorough medical-art practitioner who never puts conjecture in the place of perception and never assumes (without carefully spying out all of the disease manifestations) that the treatment for a case of disease entrusted to him is either entirely or partially known. This is all the more the case here since each reigning epidemic is in many regards a phenomenon of a particular kind that is found, by exact investigation, to deviate greatly from all former epidemics (which have been falsely labeled with certain names). This is true of all contagious diseases except those that stem from an invariable infectious tinder, such as smallpox, measles, etc.