The low concentration of homeopathic remedies, which often lack even a single molecule of the diluted substance, has been the basis of questions about the effects of the remedies since the 19th century. Modern advocates of homeopathy have suggested that "water has a memory" – that during mixing and succussion, the substance leaves an enduring effect on the water, perhaps a "vibration", and this produces an effect on the patient. This notion has no scientific support.[*][**] Pharmacological research has found instead that stronger effects of an active ingredient come from higher, not lower doses.
via Homeopathy - Wikipedia, the free encyclopedia.
Every now and then, when I worry about giving people too little credit, I like to remind myself that homeopathy exists and is widely practiced.