The aphorisms 47 and 48 discuss the need for similar medicine.
Nothing could teach the physician in a plainer and more convincing manner than the above, what kind of artificial morbific agent (medicine) he ought to choose in order to cure in a sure, rapid and permanent manner, conformably with the process that takes place in nature.
Neither in the course of nature, as we see from all the above examples, nor by the physician’s art, can an existing affection or malady in any one instance be removed by a dissimilar morbific agent, be it ever so strong, but solely by one that is similar in symptoms and is somewhat stronger, according to eternal, irrevocable laws of nature, which have not hitherto been recognized.
So Hahnemann is arguing here that the above examples of cures taking place in nature and the observations regarding what happens when two dissimilar diseases meet in a body, should be sufficient to convince everyone that only a medicine that is able to produce a similar morbid state is capable of bringing about cure in a certain, rapid and permanent way.
He says that neither in nature, nor by the allopathic or antipathic employment of medicine, can a cure take place. The strength of the antipathic or allopathic treatment cannot change this truth either. It can palliate or suppress or create a complex disease, but the non-homeopathic employment will never be able to cure. The cure can only be possible if the medicine or method is able to produce a state similar to the existing disease state. And the state created by the medicine or method should be slightly (somewhat) stronger. I have said this earlier too – the choice of words ‘slightly’ or ‘somewhat’ is significant. It reflects on the need for the cure to be gentle and quick. If the artificial disease state is too strong, it will either cause a strong aggravation or will linger on for a very long time even after the natural disease state has been removed. This goes against the fundamental premise that a cure has to be quick and gentle. I have explained these terms in great detail in my lecture on aphorism two.
Hahnemann also says that the law of similia was not recognized by anyone before him. This statement is only partially true. Several medical authorities before Hahnemann mentioned the law too. It is mentioned in Ayurveda; Hippocrates and several others mentioned it too. Hahnemann himself has given several examples in the last few aphorisms, where other doctors had observed the natural cures based on similarity taking place. He also mentioned about such people in his introduction to the Organon. However it was Hahnemann who recognized its true potential and built a whole system of medicine around it.