Symbols are the imaginative signposts in life. Margot Asquith

A very powerful traditional symbol for healing is the placebo, which is familiar to all of us. Recently there has been a great deal of research into the placebo effect, because it is so strong. Many researchers would love to capture its "magic" and use it clinically. An example of the power of the placebo is that the SSRI drugs used for depression have to have huge numbers of people in their trials, because the placebo effect is so high that statistical significance of the drug's efficacy over that of the placebo effect is not reached with smaller numbers of trial participants.

Could the placebo itself be a drug? From a May 9, 2010 article in the Boston Globe, entitled "The Magic Cure":

In the last decade-plus, however, the accumulating data have sparked a renewed interest in the placebo as a treatment in its own right. Numerous studies have shown that it can trigger verifiable changes in the body. Brain scans have shown that placebo pain relief is not only subjectively experienced, but that in many cases the brain releases its own internal painkillers, known as endogenous opioids. (This placebo effect can even be reversed by the opioid-blocker naloxone.) Another study, published in Science in 2009, found that patients given a topical cream for arm pain showed much less pain-related activity in the spinal cord when told it was a powerful painkiller. A 2009 study found that patients benefited as much from a fake version of a popular spinal surgery as they did from the real one; asthma patients have shown strong responses to a mock inhaler.

Some claim that the healing power of symbols is due to the person's belief that they work.

Wrong, according to a groundbreaking study published in PLoS One. Researchers asked patients suffering from irritable bowel syndrome (a common, hard-to-treat disorder with mostly subjective symptoms) to take placebo pills twice a day. They told participants that the pills had no active ingredients, but—this is key—they also explained that placebos can improve IBS symptoms "through mind-body self-healing processes. By the end of the three-week trial, 59 percent of pill takers (vs. 35 percent of controls) reported adequate relief. The placebo also doubled the degree of symptom reduction and improvement in quality of life.

In effect, the researchers in the IBS case were being modern day shamans.