The frequent and formidable disease on the investigation of which we are entering, cannot be understood until clear and exact answers are obtained to the following inquiries. 1. What is the series of phenomena which constitutes fever? 2. What are the particular phenomena which are common to all its varieties and combinations? 3. What is the order in which these phenomena occur in the series? 4. What are the organs, and what are their states, upon which these phenomena depend? 5. What are the external signs of these internal states, or what are the indications by which their existence may be known? 6. What is the external noxious agent or agents, or the exciting cause or causes of the disease? 7. What is the particular remedy, or the particular combination of remedies which is best adapted to each state of each organ? When these questions can be clearly and perfectly answered, and not till then, we shall know the disease and its treatment. In order to make any real progress in this knowledge we must therefore prosecute these inquiries. It appears to me that we are already in possession of ascertained facts, adequate to answer with a high degree of certainty, though perhaps not with absolute certainty, several of these questions. In keeping these inquiries steadily before our view in our investigation there will be this great advantage, that it will enable us clearly to perceive what we really know and what still remains to be ascertained. The phenomena which constitute fever, like those which belong to all the processes of nature, consist of a certain number of events. The events which take place in this disease are before our eyes: they are abundantly familiar to us all: no one man indeed has seen all the forms of fever which exist, nor observed all the symptoms of those species which he has witnessed, but accurate records are to be obtained of them all: records upon which we have this assurance that we may rely, that all the important events in this disease are so obvious and striking, and indeed force themselves so powerfully and constantly upon the notice, that there can be little danger that any one of consequence should be overlooked. Accordingly medical writings abound with the most minute, and, as far as can be judged, accurate histories of the symptoms which accompany all sorts of fevers, whether epidemic or sporadic. It is not in the observation of symptoms that the danger of error lies, because these are matters of sense, but the danger arises from a different source. Supposing, for example, that all the important events which accompany all the important varieties of fever have been ascertained, and that thus our first inquiry relative to the series of phenomena which constitutes the disease, is answered, still as many of these events are observed to be often absent, while it cannot be doubted that fever is nevertheless present, we must necessarily enquire in the next place, what is that particular combination of events which is