1. _Synochus with Subacute Cerebral Affection_, may be attended for several days with no symptom which has not been already enumerated in the account of the mildest form of the disease. The accession is the same as in synochus mitior: the progress up to a certain period is also the same. But at the time when the pain of the head diminishes in the latter, it increases in the former. Still the pain is often not severe. He who looks for intense pain, and suspects no cerebral affection, unless accompanied with this symptom, will be surprised by what will appear to him the sudden occurrence of new symptoms, such as are immediately to be stated, which will at length open his eyes to the danger of the case, and excite his wonder, which it is not unfrequent to hear expressed, that an affection hitherto so mild, should, without any previous warning, become so formidable, and show but too manifestly that it is beyond control, and will certainly proceed to a fatal termination. The warning was given, but the sign was not understood. The descriptions of disease are commonly taken from its most acute form; and it was long the practice to derive them from this form alone, and the consequences were truly fatal. Even with the best care that can be taken in drawing up the history, these descriptions are exceedingly apt to become ideal, and not real entities: to consist of a collection of all the circumstances that exist in all cases, and not of that particular combination only which is found in any one case: and thus to be not the portrait of any individual, but a fancy picture bearing a general resemblance to all individuals without being the true likeness of any. The consequence is, that at the bed-side of the sick the original from which the picture is supposed to be taken is not to be seen, and the practitioner remains in doubt, if he do not fall into error. Error serious and fatal many have fallen into, and, on this very account, still continue to fall into, with regard to the existence of cerebral disease in fever. Abundant evidence will be given in the pathology, that it is not uncommon for the most unequivocal and extensive changes of structure to take place in the brain and its membranes without severe pain having ever been felt. Pain, however, though it be not great, is almost always present. It is seldom that the pain extends over the whole head; the patient generally points to some particular part where it is peculiarly felt. In the majority of cases the seat of the pain is either in the forehead, or at the temples, or over the eyes; but occasionally it is in the occiput, and extends down the neck, and in these instances it is often severe between the shoulders.