With such minuteness of observation as this, the Materia Medica of Homœopathy must contain a _mass_ of facts, _if they really are facts_. They are claimed to be such, established by numerous and careful observations. Let us see how this is done. If an individual take an article, his condition is watched for some length of time, according to the duration of the effect of the article. This is various. The effect of carbonate of lime (common chalk) lasts fifty days; saltpetre, seven weeks; red pepper, twenty days; salt, fifty days; &c. If then common salt, for example, be the article, all bodily conditions, all sensations, all mental states, &c., occurring within fifty days, are to be set down as the effects of that salt. A collection of many such histories of cases is used in making up a complete description of the effects of this article. And so of other articles. The four hundred pages of descriptions of the effects of remedies in Jahr’s Manual are, according to the statement of Hering in his introduction to it, made up precisely in this way. If all action in the human system were produced only by what is applied to it from without, and if the system could be so insulated that only one thing at a time should be permitted to act upon it, in this case, and in this only, would such kind of observation be available. But how is it? _Numerous_ agents are constantly acting upon the system—food of various kinds—air, through the medium of the skin and the lungs—variations of temperature—varying electrical and other states—mental influences—processes resulting from previous impressions—all these exert a constant influence, modifying the effects of remedies almost infinitely. Some allowance is indeed made or affected to be made, by Homœopathists, for _some_ of these influences; but, after all, the remedy administered is considered as overtopping them all—it has _supreme_ possession of the patient, by virtue, I suppose, of its _dynamic_ power. All symptoms that can be observed in him, whatever they may be, are the effects of the medicine, and Hahneman considers the various influences of which I have spoken as only modifying these effects, and that to a limited degree.