This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
In the present state of medicine every attempt which we make to treat disease by the administration of medicine partakes more or less of the nature of experiment, because we can rarely be absolutely certain that the drug will have precisely the effect which we desire. As the phrase is, 'We try one medicine, and then we try another.' If human life were not so valuable, we might pursue a series of systematic experiments, and gain valuable information; but it is impossible for a physician to treat the patient who calls upon him for aid in any other way than that which seems likely to be the best for the patient's welfare. Here again the homoeopathists have done good service, because by administering to the patient medicines in which they believed, but which could neither do good nor harm, they have taught us the natural course of some diseases, which we could not otherwise have learned.