[98] Great nicety is required in all cases with regard to the times and doses of cordials; for it by no means follows that these should be in proportion to the lowness and loss of strength. This is well illustrated by Mr. Hunter in his Lectures, where he explains the distinction between the powers of the body and its _actions_. There must be a certain degree of strength to bear the excitement occasioned by stimulating and strengthening medicines or diet; for nothing is more pernicious, or even fatal, than that any part or function should make exertions beyond its strength; and there is the more danger in ill-timed remedies of this kind, as a state of weakness is generally a state of irritability. [99] See a method proposed for obviating this, page 358. [100] Page 381 et seq. [101] Sailor’s fever. [102] See pages 161, 181, and 380-1. [103] I have in the whole of this work been extremely cautious in reasoning concerning causes, from an opinion that they are very obscure, and that the theoretical part of physic is very imperfect and fallacious. This is perhaps in no instance more remarkable than in those opinions that prevail concerning the nature and influence of bile in producing diseases. An increased secretion of bile commonly attends the feverish complaints of hot climates, and those of the hot seasons of temperate and cold climates. It is not unnatural, therefore, to impute the disease then prevailing to this redundancy of bile: but, upon considering the matter more closely, it will appear to be rather a concomitant symptom, or effect, than a cause of those fevers; for, in the first place, in those cases in which there is the greatest secretion of bile, as in the _cholera morbus_, there is no fever. The only danger in this disease arises from the violent irritation produced in the bowels by such an extraordinary quantity of this secretion which commonly passes downwards; though I have seen it prove fatal when it flowed into the stomach, and produced perpetual retching and excoriation of the fauces; but in this case also without any fever. Secondly, in the most fatal of all fevers, in the West Indies, there are no marks of an increased secretion of bile, but, on the contrary, a preternatural defect of it, as appears by its not being evacuated either by stool or vomiting, by the white stools which sometimes attend the yellow fever, and by its not appearing in the first passages, nor in its own receptacles after death. Perhaps also that state of the bowels which renders it so difficult to procure stools may be in part owing to the want of this natural stimulus. It is nevertheless true, that in the intermitting and remitting fevers of hot climates and seasons there is perhaps always an accumulation of bile at the beginning, and an increased secretion of it during their course. It is farther true, that this adds to the patient’s uneasiness, and aggravates the symptoms, and that the cure consists partly in the evacuation of the bile.