have, as their common characteristic, a profound and specific lesion of the elliptical patches.' No bolder attempt than this has ever been made to build up an original theory or hypothesis; and yet it is scarcely put forth before the discovery is made, that the lesion which is here considered so essential to the existence of fever, is not a constant concomitant. It can, indeed, only be determined to exist at all by post-mortem examination. A single exception, you will perceive, is fatal to the whole system; and there is now no reason to doubt that fever very often exists without either inflammation of the intestinal mucous tissues, or of the glands of Peyer. Neither can, therefore, be considered an essential cause or condition. It seems, moreover, more than probable that both these lesions, when they exist at all, are the effects of fever. These theories of the French school, therefore, which have been so confidently announced, and so trustingly received, present no stronger claims upon our confidence than those which preceded them; nor do they promise more durability. Indeed, one can hardly examine the various theories of fever, which have up to the era of Louis been promulgated, and contemplate the errors in practice which have resulted from them, without acknowledging the truth of the maxim of Cayol, one of the critics of Louis: "Systems in medicine are idols, to which human victims are sacrificed." The student of medicine is expected to inform himself in regard to the character of the prominent hypotheses which have been published; but the natural effect upon the minds of those who are in pursuit of truth is, to impress them with the uncertainty which must ever attend upon the most able and ingenious, founded in any degree upon assumed data. It is be- . cause of this unsubstantial basis that so large a number have been promulgated upon this subject. Each has had its adherents, who were ready to subscribe to every assumption, and every dogma; and the duration of one seems to have been limited only by the appearance of another to take its place. As each in its turn has occupied the attention, and secured the confidence of the profession, it has required considerable moral courage to question its soundness; but you may safely consider, that what has been written in explanation of fever hitherto is merely hypothetic; and you will do well to believe, that theories in medicine, as in other branches of science, must always be founded upon well-established facts, without which they are not entitled to confidence. Whatever may have been said of fever as proceeding from the influence of local irritation, it is not now to be doubted that whenever it exists, it involves the whole system in its abnormal action. In general, if not always, it is a mild disease in its early stages, insomuch that it is not an easy matter, in many cases, to determine the actual period of its beginning. In its slow and gradual progress to greater and greater intensity, it affects the system somewhat unequally, in some parts more than in others, according to the degree of susceptibility of different organs and tissues; until, finally, when the disease becomes developed, and symptoms of serious import arise, some one organ or tissue is found to be more particularly implicated than the rest, causing much suffering from the local as well as from the general disease; and it is just at this period that the advice of the physician is most likely to be required. He finds the patient suffering with fever, the attack being generally referred to that period in its progress in which a distinct chill, or other painful symptom, occurred. But if diligent inquiry be made, it will be found that the first signs of disease appeared at an earlier date, often several days, and sometimes even weeks, before the true character of the ailment was discovered. I shall have occasion, probably, to refer to this matter again, but I mention it now to enable you to account, in some measure, for the discrepancy in the views of those who have thought themselves called upon to construct systems in medicine; and also to deprecate the fact, that this slow and insidious character of fever, in its approaches, has hitherto been too little noticed by authors. I shall attempt to show you, too, as we go on with the course, that fever, in all its various forms and grades, is, in its inceptive stage, a mild and tractable disease, even when prevailing as a fatal epidemic. In thus condemning the views of so many distinguished writers on fever, all of whose ingeniously constructed systems have proved to be only ephemeral, it is not my intention to propose one of my own. I have none to offer. If you ask me what I consider to be the true cause and pathology of fever, I must express to you my belief that these yet remain to be discovered; and when we consider what have been the labors and researches of the ablest men in our profession, it seems quite strange that greater discoveries have not been made. So it is, however, and we must look to the future for instruction upon these subjects, without much dependence upon the past. New means and appliances of investigation are coming constantly into use, and possibly the facilities to be afforded for chemical analysis, and for microscopic observation, together with a more thorough acquaintance with the workings of the nervous system, may ere long reveal what has hitherto been hid from human scrutiny. At the present time, we must patiently content ourselves with the rules adopted by philosophers in reference to the imponderables, known only from their effects. The time is past, I judge, |