In 1991, Alexander Shulgin, a pioneering chemist and pharmacologist, published PiHKAL, a book that would become a cornerstone of the psychoactive community. The book is a detailed exploration of phenethylamines, a class of compounds that are structurally related to the neurotransmitter phenethylamine. Shulgin's work provides an exhaustive catalog of over 200 phenethylamines, each with its unique chemical and pharmacological profile.