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ledge existing at the time. They are also usually illustrated by morbid preparations and drawings, which are rarely accessible to the mere reader of books. But they labour under the same defects as books, of not bringing the student into direct intercourse with the sick. They have this additional drawback, that the lecturer is apt unduly to impregnate his hearers with his own opinions, to the exclusion of those entertained by other teachers on the same subject. This is more likely to occur with oral instruction than with books, because the living man seen and heard is more apt to bulk in the eye and to influence the judgment of the student than the author of a treatise whom he has never met. When a man learns all by reading, all his instructors are placed on the same level, and no one takes undue precedence over the rest.
Clinical instruction differs from both the methods of study just mentioned in this, that it deals with cases of real disease present in the hospital, and subjected to all the details of actual treatment. It has this great advantage, therefore, that it affords the student opportunities of seeing living examples of what he wishes to study, and of exercising his faculties in investigating them. He no longer trusts to the ipse dixit of his teacher, or to the dogmatic statements of any author, however learned. He tests every assertion for himself, and withholds or accords his assent as his judgment is convinced. And although in nine cases out of ten, where a difference of opinion exists between him and his teacher, it will be found that his teacher is right, and he is in error; yet scepticism has this great advantage in this instance, that it leads him but the more carefully to put everything to the proof, and to be satisfied with nothing short of absolute conviction.
If you trust to what you read in text-books, there ought to be no difficulty, for example, in distinguishing between an endocardial and an exocardial murmur, or between the friction sound of pleuritis and the crepitus of pulmonary inflammation, yet it often happens that these various sounds, essentially distinct, when fully developed, approximate so closely to one another in their embryo conditions, that it
