Every student of clinical medicine must become acquainted, as soon as possible, at the bedside, with these tokens and evidences, which make almost the alphabet of practice: What is a good, a doubtful, and a bad pulse? How does a patient breathe when moribund from simple exhaustion, and how does such respiration differ from the toil and struggle of asthma or the stertor of narcotism? Why does a glance suffice to make known to a surgeon the state of collapse after a railroad accident, or to a physician that of cholera or pernicious intermittent? What is the impression given to the finger upon the skin by intense fever, and what by the relaxation which precedes death? These and many other such questions are to be answered fully to each student only by the use of his own senses, with such interpretation as is to be obtained by the careful comparison of cases, with the aid of books and didactic instruction. To a well-trained eye and hand a look and a touch will often suffice to make known the commencement of convalescence or of the precipitous decline toward death. Yet a wise physician will be very cautious in acting upon even seemingly obvious prognostications. Changes may be going on in important organs whose effects have hardly yet begun to show themselves, and which may after a while materially alter the aspect of the case. Particularly near the beginning of an attack of enthetic disease, such as scarlet fever, small-pox, typhus or typhoid fever, the physician should beware of too confidently forecasting the progress of the case for better or for worse. In nothing, probably, is the prudence of a practitioner more often or more severely tested than in his answers to inquiries made concerning prognosis. 4. Anticipation of the modifying action of remedies is undoubtedly a proper factor in our estimate of the probable result of any case of illness. Few diseases, however, are as yet so subject to control by specific medication as to allow certainty in such expectations. In a first attack of ague we may look with much confidence toward the speedy cure of our {170} patient under quinia. In one who has had chills all winter even this confidence may need qualification. A sufferer with syphilitic rheumatism may generally be promised relief under the use of iodide of potassium, or one afflicted with scabies under the application of sulphur ointment. We seldom have misgivings about our ability to give relief in colic, constipation, or diarrhoea. Yet the first two of these may prove to be symptoms of intestinal obstruction resisting treatment, and the last may depend upon chronic ulceration of the bowel, giving it unexpected continuance. In all such instances careful and (when practicable) accurate diagnosis must precede prognosis; our estimate of the action of remedies becomes then a secondary, although often a valuable, part of the calculation of the probabilities of the case.