Parkes, writing in Reynolds’ System of Medicine in 1876, views the subject more as we see it today: “The rapidity of the spread would seem at once to negative any connection between human intercourse and the propagation of the disease; yet there is some affirmative evidence. It does not appear to follow the great lines of commerce; but when it has entered towns and villages in which the investigation can be carried on, it is curious how frequently the first cases have been introduced, and how often the townspeople nearest the invalids have been first affected. In this country especially, Haygarth in 1775 and 1782, and Falconer in 1802, collected so many instances of this that they became convinced that its propagation was due entirely to human intercourse. So also, when it passes through a house, it occasionally attacks one person after another. But if it is introduced in this way it afterwards develops with marvelous rapidity, for we cannot discredit the accounts of many thousands of persons being attacked within a day or two, which is quite different from the comparatively slow spread of the contagious diseases. This _sudden_ invasion of a community makes it, to many persons, appear highly improbable that any effluvia passing off from the sick should thus so rapidly contaminate the atmosphere of a whole town. “Still, we must remember how singularly, of late years, the knowledge of the introduction of cholera by persons coming from infected districts has increased, and how very striking are the instances of this kind already recorded in several works on influenza. “In some cases, again, isolation or seclusion of a community, as in prisons, has given immunity; or at least that community has not been attacked.” The great rapidity of spread has caused even in 1918 some temporary doubt as to the contagiousness of the disease. Thus, Zinsser wrote: “The opinion of direct and indirect transmission from man to man is also well supported by a detailed study of the epidemiology of individual outbreaks. In our own experience with epidemics such as those at Chaumont, Baccarat and other places, the suddenness with which the malady attacked large numbers of people at almost one and the same time, caused me at first to be exceedingly skeptical of accepting transmission by contact as the only means of conveyance. We considered food and insect transmission as possibilities, and tried our best to find grounds for involving such agencies. But in every case we were forced to return to the conclusion that direct and indirect contact between men came nearest to doing justice to all observed facts.”