The analysis of an epidemic does not involve the recognition of the general form of the disease, by placing it in the abstract space of nosology, but the rediscovery, beneath the general signs, of the particular process, which varies according to circumstances from one epidemic to another, and which weaves from the cause to the morbid form a web common to all the sick, but peculiar to this moment in time and this place in space; in Paris, in there was an epidemic of quartan fever and putrid synochus, but the essence of the epidemic was that 'the bile had dried up in its passages and turned into melancholy, the blood had become impoverished, thickened, and sticky as it were, the organs of the lower part of the abdomen had swollen and become the causes or centres of obstruction',' or a sort of over all singularity,