The first principle of the medical art, therefore, is founded upon a knowledge of the relations subsisting between the various states of the animal functions and the power of medicines, as exhibited in the preceding sketch of a natural system; and it consists in the application of the articles of the different genera of medicines (exhibited in the last column of the table) to the cure of the corresponding genera of disease (exhibited in the third one). * * * * * One of the most beautiful results of the principle I have proposed is, that, by its adoption, it will be possible for the physician to lay his hand upon the several columns of a table, each of which, with regard to the diseases which it enumerates, is precisely similar in its nature from commencement to end; indicates correspondingly arranged articles of the materia medica, and requires precisely a similar mode of cure. As the same arrangement is applied to the articles of the materia medica, the corresponding medicine will evidently, in every case, readily present itself to him. But the most signal advantage resulting from it is, that, by merely assigning to any disease its place in nosology, the physician will instantly indicate the mode of cure which ought to be adopted for it. I shall now then, Gentlemen, conclude by this important remark, that happily the tendency of this natural system of disease is not to controvert one established fact, but, by pointing out their relations, to simplify, consolidate and if possible to increase the amount of our knowledge on all the subjects of medicine. SECOND PRELIMINARY LECTURE TO THE COURSE OF PATHOLOGY AND THE PRACTICE OF MEDICINE; EXHIBITING A FUNDAMENTAL PRINCIPLE OF SURGICAL OPERATION. GENTLEMEN, The vague plans of Surgical operation, at present practised, are too generally known, and too sincerely deplored, by every man of science and of feeling, to demand much of comment on the present occasion. How often, in the attempt to take up an artery, does the ignorant and timid operator make an incision so limited that he is afterwards forced cruelly to extend it! How often, having extended his incision, does he find no artery beneath it, and dig or mine for it in a new direction, by cutting up the flesh of the patient! How often, having reached the place he sought for, does he mistake another artery, a nerve, or even a vein, for that which ought to be the subject of operation! How often, having found the artery, is he at a loss to recognize it! What trepidation and alarms does not this operator, more miserable than the patient himself, endure!