An entheogen, in the strictest sense, is a psychoactive substance use in a religious or shamanic context. Entheogens generally come from plant sources which contain molecules closely related to endogenous neurochemicals. They occur in a wide variety of sacraments of various religious rites [UDV/NAC] and have been shown (see Good Friday Experiment) to directly provoke what users perceive as spiritual/mystical experiences. In a broader sense, the word "entheogen" refers to any molecule which stimulates the central nervous system through one of the two main neurological pathways: Phenethylamine (which is a brain chemical associated with the adrenaline pathway, and a precursor of Mescaline and 2C-B) and Tryptamine (a brain chemical associated with the natural metabolism of serotonin, a precursor of Psilocin), DMT. (Biochemical Basis of Neuropharmacology, Cooper Bloom Roth - PIHKAL, Shulgin) In the aforementioned books the pathways of the neurochemicals are described as occurring from simpler precursors. Through enzyme reactions, the brain creates more complex molecules with a higher binding affinity with unique neurological and cognitive results. See Federal Analog Act.