[27] Dr. Holmes says of this pre-eminently talented and learned man—“Berkeley died at the age of about seventy; he might have lived longer, but his fatal illness was so sudden that there was not time enough to stir up a quart of his panacea. He was an illustrious man, but he held two very odd opinions; that tar water was everything, and that the whole material universe was nothing.” [28] The bare fact that death results is obviously no proof of the want of skill, any more than the bare fact that a case has ended in recovery is proof of the possession of skill. But the disposition to which I have alluded is quite common, and gives rise to many unjust conclusions in regard to the merits of physicians. Hence physicians often manifest, in various ways, a dread of having the charge of cases, which are sure to end fatally. Some, to avoid the imputation of “bad luck,” as it is expressed, often manage adroitly to throw such cases off from their own hands into those of some neighboring practitioner, or some empiric, before death actually occurs. CHAPTER IX. THEORY AND OBSERVATION. All real knowledge is based upon observation; and it is the facts discovered by observation, which, accumulating from age to age, constitute the _store_ of human knowledge. Not a single grain has ever been added to this store, in all the ages of the world, through the instrumentality of theory alone. Theory, or hypothesis, has often suggested the existence of facts, and has directed in the pursuit after them, but observation after all is the only agent that has discovered them. Facts are of two kinds—particular and general. General facts are discovered by a careful observation of a great number of particular facts. Thus Newton, by observing many particular or individual facts, established the general fact, which is called gravitation, viz., that all bodies are attracted towards each other, or have a tendency to come together. So in medical science, by an observation of many facts in individual cases, it has been discovered, that there is a tendency in the human system to restoration to health, whenever it is attacked with disease—a tendency, existing as a general fact, to which has been given the name, _vis medicatrix naturæ_.