Let the student read Dr. Meigs’s 140th paragraph soberly, and then remember, that not only does he infer, suspect, and surmise, but he actually asserts (page 154), “there was poison in the house,” because three out of five patients admitted into a ward had puerperal fever and died. Have I not as much right to draw a positive inference from “Dr. A.’s” seventy exclusive cases as he from the three cases in the ward of the Dublin Hospital? All practical medicine, and all action in common affairs, is founded on inferences. How does Dr. Meigs know that the patients he bled in puerperal fever would not have all got well if he had not bled them?
“You see a man discharge a gun at another; you see the flash, you hear the report, you see the person fall a lifeless corpse; and you infer, from all these circumstances, that there was a ball discharged from the gun, which entered his body and caused his death, because such is the usual and natural cause of such an effect. But you did not see the ball leave the gun, pass through the air, and enter the body of the slain; and your testimony to the fact of killing is, therefore, only inferential,—in other words, circumstantial. It is possible that no ball was in the gun; and we infer that there was, only because we cannot account for death on any other supposition.” [Chief Justice Gibson, in Am. Law Journal, vol. vi. p. 123.]
“The question always comes to this: Is the circumstance of intercourse with the sick followed by the appearance of the disease in a proportion of cases so much greater than any other circumstance common to any portion of the inhabitants of the place under observation, as to make it inconceivable that the succession of cases occurring in persons having that intercourse should have been the result of chance? If so, the inference is unavoidable, that that intercourse must have acted as a cause of the disease. All observations which do not bear strictly on that point are irrelevant, and, in the case of an epidemic first appearing in a town or district, a succession of two cases is sometimes sufficient to furnish evidence which, on the principle I have stated, is nearly irresistible.”
Possibly an inexperienced youth may be awe-struck by the quotation from Cuvier. These words, or their equivalent, are certainly to be found in his Introduction. So are the words “top not come down”! to be found in the Bible, and they were as much meant for the ladies’ head-dresses as the words of Cuvier were meant to make clinical observation wait for a permit from anybody to look with its eyes and count on its fingers. Let the inquiring youth read the whole Introduction, and he will see what they mean.