The positive effect of quinine on fever was well known in Hahnemann’s time. He tried the effect of cinchona on himself, and described what happened when he twice a day consumed two points of a knife of "good cinchona": "First the, feet, then the tips of my fingers etc. became cold, then my heart started beating, the pulse heavy and fast; then I was possessed by an infinite anxiety, a trembling (but without shiverings of cold), a weakening of all limbs, then beating in the head, reddening cheeks, thirst - in short, all the symptoms of relapsing fever presented themselves successively . . ."
During this trial on himself Hahnemann drew the conclusion that quinine is able to cure malaria, because it could cause the same symptoms as malaria on healthy people. This is the basic principle of homeopathy. Hahnemann’s principle, Simila similibus (similia similibus curentur) («with the help of the same»), both formally and in its content it is a declaration of war on traditional medicine, which from Antiquity had been based on the principle contraria contrariis («with the help of the opposite»).