An undue attachment to certain modes of investigation, to the exclusion of others, is also frequently a source of error. I mention as an example a too implicit and exclusive reliance upon what are called the physical signs of disease. Percussion and auscultation are valuable sources of evidence, but when they are relied upon to the exclusion of other sources, as is often the case, they lead to error. Some who have attained to a high degree of skill in the use of the stethoscope, have on this account sometimes adopted very erroneous conclusions, which might have been avoided by a careful examination of _all_ the sources of evidence in the case. Having pointed out some of the errors produced by narrow and exclusive views in the investigation of the symptoms of disease, let us now attend to some of the errors which result from this cause, in the _application of remedies_. A remedy may be applicable to a disease which the physician finds developed in a given case, but there may be some condition of some organ, which may render it wholly inapplicable to that case. For example, in a case of inflammation of the lungs, the state of the stomach may be such as utterly to forbid the use of some remedies, which would otherwise be proper. If they be administered in spite of this circumstance, they may perhaps produce a beneficial effect upon the inflammation, and yet may do a great injury to the patient, perhaps even a fatal one, by their direct effect upon the diseased stomach. Errors of this kind do often occur in the practice of those who observe inaccurately, or who have fallen into a sort of routine of practice from disinclination to mental effort. The general condition of the patient sometimes fails to be appreciated by the practitioner. He may be pursuing a course which would be admirably adapted to cure the same disease in a more vigorous patient, and yet in the case in hand it may be ruinous. Though it may relieve and even cure the disease, it yet may destroy the patient. The judicious physician in some cases feels obliged to let morbid processes go on, because the violence which must necessarily be done to the debilitated system by the attempt to arrest them, would put the patient’s life in greater jeopardy, than it would to let them have their course. Questions frequently arise on this point, which tax the physician’s skill and judgment to the utmost. Even when it is proper to moderate the activity of a diseased process, it is often a very delicate point to determine just how far this can be done without doing harm to the patient. Fever is often moderated by means that irritate the system, or prostrate its powers to such an extent, that bad results, sometimes fatal ones, occur; when, if these means had been used less largely, or perhaps even if they had not been used at all, a recovery might have taken place.