The preceding history of the symptoms of fever can be of no real use unless it be possible to connect it with the events of which those symptoms are the signs. The events consist of certain morbid changes which take place in the series of organs already enumerated. We arrive at the knowledge of these events first by noting the symptoms which occur during life, and their order of succession: and, secondly, by examining the condition of the organs after death in the fatal cases: a comparison of the symptoms, as previously observed, with the state of the organs as subsequently ascertained, teaches us what the symptoms indicate. By carefully observing the symptoms in a large number of cases, we at length become acquainted with all the important symptoms that arise: by carefully examining the organs after death in a large number of cases, we gradually learn all the important changes in structure which they undergo: and by comparing, in all cases, the morbid symptoms with the altered states, we acquire in the end the power of ascertaining, with a high degree of probability, the presence of an event which we cannot see, by the presence of its sign which we can see. In proportion as our knowledge becomes perfect, we are thus enabled, during life, and at the bed-side of the patient, to see what is going on within his brain, within his lungs, and within his intestines, with as much distinctness and certainty as we could were the cases in which these organs are enclosed, and the organs themselves transparent. The highly interesting and important fact demonstrated by the examination, in the manner of which we have just spoken, of large numbers of fever patients is, that the changes which take place in the organs are uniform; that the symptoms by which these changes are denoted are likewise uniform, and therefore, that it is possible to arrive at a perfect knowledge of the phenomena of fever. The present state of our knowledge, it must be confessed, is far from being perfect. To a certain extent, however, it is even already sufficiently perfect to afford the physician an invaluable guide in the conduct of his practice; and the steps that are wanting to complete the knowledge we possess (as far as human knowledge can be complete) future labour and perseverance will assuredly supply.