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and capable of telling by rote all that had been written about it, has failed to recognise a case of it when presented to his notice, simply because he never had enjoyed the opportunity of making himself acquainted with its general features. You all know how difficult it is to picture to yourself the appearance of a friend whom you have often heard of but have never seen. Let his photograph be sent home, and your ideas will become more definite; yet even then you may, perhaps, pass him in the street, because you have not yet caught the true expression of his features as they are displayed under the varying emotions of actual life. But as soon as you have been introduced to him, and have become familiar with his aspect and appearance, every thing is changed. You recognise him at a glance, and even at a distance, when his features are too far off to be distinctly seen, his very gait and manner and dress will be sufficient to identify him. The same thing is true of disease. Verbal descriptions are all very well in their way, but they fail to make the vivid immediate impression on the senses that the constant habit of observing living examples is sure to do. Here, then, is the grand defect in books as a method of studying medicine—and I mention it to warn you of the mistake of thinking you can safely neglect the opportunities afforded by the wards of the hospital, in the hope that you can make up for them afterwards by reading in your closet—they give no room for the proper training of your various senses in the observation of disease. It is only by actual and repeated use at the bedside of the patient, that these essential instruments for the detection of morbid phenomena can be educated to their peculiar function. What verbal description, for example, will give you such a clear conception of the peculiar aspect presented by a patient labouring under fever or pneumonia as a single glance at a characteristic specimen will do? These are all what Locke calls simple ideas, and are only to be acquired by the actual perception of each by its appropriate sense.
The only other defect that I shall notice under this head is, that the statements contained in books as to the efficacy of par-
