Which of us has not heard fifty times, from one or another, a nurse, or a friend of the sick, aye, and a medical friend too, the following remark:--"So A is worse, or B is dead. I saw him the day before; I thought him so much better; there certainly was no appearance from which one could have expected so sudden (?) a change." I have never heard any one say, though one would think it the more natural thing, "There _must_ have been _some_ appearance, which I should have seen if I had but looked; let me try and remember what there was, that I may observe another time." No, this is not what people say. They boldly assert that there was nothing to observe, not that their observation was at fault. Let people who have to observe sickness and death look back and try to register in their observation the appearances which have preceded relapse, attack, or death, and not assert that there were none, or that there were not the _right_ ones.[5] [Sidenote: Observation of general conditions.] A want of the habit of observing conditions and an inveterate habit of taking averages are each of them often equally misleading. Men whose profession like that of medical men leads them to observe only, or chiefly, palpable and permanent organic changes are often just as wrong in their opinion of the result as those who do not observe at all. For instance, there is a broken leg; the surgeon has only to look at it once to know; it will not be different if he sees it in the morning to what it would have been had he seen it in the evening. And in whatever conditions the patient is, or is likely to be, there will still be the broken leg, until it is set. The same with many organic diseases. An experienced physician has but to feel the pulse once, and he knows that there is aneurism which will kill some time or other.