The present paper exposes hallucinogens from several points of view. These diverse lateralities indicate the basic lack of scientific and antropological support for the psychogenic nature of a hallucinogen. This paper seeks to de-demonize that reputation and expose its history, anthropology, chemistry and pharmacology. It is possible that hallucinatory plants were amongst the first botanical specimens used by mankind in his religious ceremonies. Uses such as divination, weather prediction, contact with spirit and ancestral worlds, were among some of those shamanic functions. The study engages in chemical analysis of the different structures that appear principally responsible for hallucinatory experiences. The latter as respects LSD-25 as a special case. The pharmacology of hallucinogens is quite vast and the present paper discusses only some of the compounds. A three phase classification is also mentioned as an explanation of the hallucinatory experience itself.