Something there is, however, which, amidst this astonishing diversity, preserves the identity of the disease so completely and so obviously, that there never has existed any dispute about that identity, under any aspect which it has hitherto been observed to assume; so that all physicians, without exception, unhesitatingly accord the name of fever to the mildest form of the common fever of this country, to the yellow fever of the West Indies, and to the plague of Constantinople and of Egypt. Bring three persons, each exhibiting an exquisite specimen of one of these several forms of the disease into the same ward of an hospital, the external aspect presented by each would be so different, that an unprofessional observer would probably be able to discover in these modifications of the same malady no common property: yet there is no physician who would not, in each case, instantly pronounce the disease to be fever. There must, therefore, be something that establishes the identity of the disease under this diversity of aspect. What is that something? Whatever it be, it must be common to all the varieties of fever. Thus we are led at once to the second inquiry which we proposed to keep before us in this investigation, namely, what are the particular phenomena which are common to all the varieties and combinations of the disease? The importance of making this analysis has been felt by every person who has directed his attention to this subject from the remotest antiquity down to the present time. That it is not as easy to be made as the necessity of it is plainly to be perceived is abundantly attested by the want of success which has hitherto attended the efforts to perform it of the acutest minds, and the acutest minds, the pride and boast of our science have applied themselves to the task. Notwithstanding their labours however, the analysis made by Hippocrates has been received through succeeding ages with little variation, and continues to be received even in modern times with only slight modification. And yet that reflecting men of every age have not been satisfied with resolving all the essential phenomena of fever into heat, although they have all consented to designate the disease by some term expressive of that property,[17] is attested by proofs no less striking than instructive. We are informed by Van Swieten, that Boerhaave collected with much labour from a great variety of authors all the symptoms which they had observed in different fevers: that from these he threw out such as did not appear in all fevers, and that finding himself obliged to exclude one after another, he was at length greatly surprised to find the catalogue so short; it being ultimately reduced to three; namely shivering, frequent pulse, heat.