Psychedelic substances such as ayahuasca, psilocybin, and LSD have been used for millennia in spiritual ceremonies, often producing transcendent experiences. This chapter traces their history from ancient rituals through colonization and the countercultural revolution to modern neuroscience. It explains how these compounds mimic serotonin and interact with brain receptors to alter consciousness, affecting the default mode network, ego, and self-referential processing. Such effects can produce feelings of oneness, ego death, and reductions in depression and anxiety. The chapter asks whether mystical states are supernatural or meaningful expressions of altered neural processing, and suggests that guided use with proper set and setting positions psychedelics at the intersection of brain, mind, and meaning.
Sleep paralysis is a common but terrifying experience in which a person wakes unable to move, often feeling chest pressure and a sensed presence. This chapter argues that these episodes arise from the collision of sleep architecture and perceptual ambiguity: REM-sleep paralysis persists into wakefulness, and hallucinations emerge in this liminal state. The temporoparietal junction is implicated in out-of-body experiences and the sensation of a nearby presence. The chapter offers a neurobiological explanation for a phenomenon that cultures worldwide have described for centuries, blurring the line between brain and belief.