Homeopathy or homœopathy is a system of alternative medicine originated in 1796 by Samuel Hahnemann, based on his doctrine of similibus curentur ("like cures like"), according to which a substance that causes the symptoms of a disease in healthy people will cure similar symptoms in sick people. Hahnemann believed that the underlying causes of disease were phenomena that he termed miasms, and that homeopathic remedies addressed these. The remedies are prepared by repeatedly diluting a chosen substance in alcohol or distilled water,followed by forceful striking on an elastic body, called succussion. Each dilution followed by succussion is said to increase the remedy's potency. Dilution usually continues well past the point where none of the original substance remains. Homeopaths select remedies by consulting reference books known as repertories, considering the totality of the patient's symptoms as well as the patient's personal traits, physical and psychological state, and life history.