Homeopathy is a controversial form of complementary and alternative medicine emerging from the work of the German physician Samuel Hahnemann in the late 18th century.  Homeopathy relies on the use of specific remedies which are based on substances that are believed to, in their undiluted form, cause symptoms similar to the disease they aim to treat.  Practitioners of Homeopathy dilute these specific substances through a process called serial dilution, with includes shaking the material at each stage of dilution.  Proponents believe that the dilution process removes side-effects but retains therapeutic powers.  Hahnemann proposed that this process aroused and enhanced "spirit-like medicinal powers held within a drug".  Practitioners of Homeopathy – often called Homeopaths – customize appropriate patient treatments according to consultations with the individual which reveal both the physical and psychological state of the patient.  While not well accepted by the mainstream, the main premise in Homeopathy is that every person has energy called a vital force or self-healing response and Homeopathy aims to stimulate the body's own healing responses to disease.