The Law of Similars

Organon Aphorism §22

But as nothing is to be observed in diseases that must be removed in order to change them into health besides the totality of their signs and symptoms, and likewise medicines can show nothing curative besides their tendency to produce morbid symptoms in healthy persons and to remove them in diseased persons; it follows, on the one hand, that medicines only become remedies and capable of annihilating disease, because the medicinal substance, by exciting certain effects and symptoms, that is to say, by producing a certain artificial morbid state, removes and abrogates the symptoms already present, to wit, the natural morbid state we wish to cure. On the other hand, it follows that, for the totality of the symptoms of the disease to be cured, a medicine must be sought which (according as experience shall prove whether the morbid symptoms are most readily, certainly, and permanently removed and changed into health by similar or opposite medicinal symptoms) have the greatest tendency to produce similar or opposite symptoms.

Samuel Hahnemann, Organon of Medicine, 6th edition (Boericke translation, public domain).

Expert explanation & clinical interpretation for this aphorism are coming soon.