What is Psilocybin? "Psilocybin is a psychoactive compound found in specific species of psilocybe mushrooms." (http://itech.dickinson.edu/chemistry/?p=917). Once Psilocybin is introduced to the body, it is quickly metabolized into Psilocin, which then acts on the serotonin receptors. Psilocybin is not addictive because the compound has no significant effect on dopamine receptors, which is the powerhouse for addiction. There is a wide range of uses for the fungus, starting from religious ceremonies, used as medicine, cancer, a natural anti-depressant, and other miraculous impacts on the Aztecs and Mayans culture and beliefs. As the years have passed, some modern Scientists and Psychologists and researched and studied the mushroom, and were startled by the benefits.
Hallucinogenic mushrooms have been part of human culture as far back as the earliest recorded history. Since the year 5000 B.C, ancient paintings of mushroomed humanoids have been found in caves in the Tassilic Plateau of Northern Algeria. The inhabitants, the Aztecs, called the mushroom "Teonancatl" (Flesh of Gods). Southern America built temples to mushroom gods and carved "mushroom stones". These stone carvings are believed to be dated as far as 1000-500 B.C. The purpose isn't proven to be certain, but they may have been religious objects. The fungus was also used for medicinal purposes. For example, "Shamans used the mushroom and were considered to be healers who saw into the soul of the affected in order to help with their common state." (http://itech.dickinson.edu/chemistry/?p=917). With these medical rituals, Shamans were able to directly identify the points of the patients where needed improvement, from mental to physical healing.
Today, some European Psychologists use Psilocybin to treat depression. Their conclusion of the treatment was that it was better that prescribing anti-depressants.