Shamanism is probably the oldest known form of healing, which is based on the religious belief that all illnesses are derived from an imbalance of spiritual energy. The Shamanists believe that all illnesses can be corrected by shamans (medicine men or women) who can see the spiritual forms of energy and determine whether they are in balance. A variety of substances have been utilized by shamans in the healing process including bone, wood, and pearl (see the photomicrograph above), minerals, precious stones, and some metals such as copper.