Hahnemann, by his fine observation and the inductive method of reasoning, became convinced of the law of cure, similia similibus curentur, and embraced it and declared it to be universal, a basic law of therapeutics.

If there is any general law of cure, that law must express some relationship between the medicine and the disease. To be of any practical use such a relationship must be exhibited, and we must be able to demonstrate such a relation between a disease and its remedy that any examination of the former shall determine the latter.

It is the characteristic of disease to produce certain phenomena which are not observable in perfect health. This is true whether the changes are functional or structural; what we recognise as symptoms are all that can be known of the disease. It is only through the observation of these expressions that we can make any use of the law of cure, and there can be no general consideration of the rule of cure, unless it comprises a consideration of symptoms as one of the necessary elements.

One might say that a comprehension of the symptoms of a given case was one of the primary factors, and in so far as one comprehends the expression of disease in these phenomena is one equipped to follow the law of cure in any particular case. Symptoms are the only representative expression of the diseased state. We include sensations as expressed by the patient, the appearances in all parts of the body, the varied circumstances under which these symptoms were recorded, and the varied grouping of these symptoms, in any consideration of the case.

When a symptom is noted under certain circumstances and not under others, this obvious relation between the symptom and its related circumstance is in itself a symptom, or rather, a part of the symptom, the sensation being quite incomplete without the expressed relationship of circumstance. Very often the concomitant of circumstance is of greater importance to the whole case than the expressed sensation, but the sensation is much more frequently expressed by the patient.

Two or more symptoms may appear together, or synchronize with each other, so frequently that they are really one symptom and must be considered as such in our analysis.

A law of cure must represent some relation between the properties of a disease and the medicinal qualities of a drug; or in other words, we must have some concept of the character of the drug's action on the living body that will interpret the law of cure in the action of disease.

This character of the drug is represented, not by a single effect, but by a group of effects. This group of effects is the only representation we have or can have of the medicinal character of a drug on the living body, and since these same effects are found in disease states, these effects are the only relationship that can be established between the medicinal effects of a drug and disease. There can be no law of cure unless it expresses some definite relation between these two groups, or classes.

The homoeopathic law establishes a definite relation, not only between proved drugs and known diseases, but between all the unexplored medical wealth and the undeveloped requirements of sickness. Like the law of gravitation, the law of cure as taught by Hahnemann is not, and cannot be, limited to a small group of conditions; the limitations rest entirely with our ignorance. Hahnemann and his followers constitute the only group of medical philosophers who have always been true to the inductive method of reasoning, based upon known facts, they have established this law of therapeutics.

Thus the law of cure can be seen as a crucial concept in the discipline of homeopathy, and a necessity in understanding disease and remedy.