Ethocybin (CEY-19; 4-phosphoryloxy-DET; 4-PO-DET) is a homologue of the mushroom alkaloid psilocybin, and a semi-synthetic psychedelic alkaloid of the tryptamine family. Effects of ethocybin are comparable to those of a shorter LSD or psilocybin, although intensity and duration vary depending on dosage, individual physiology, and set and setting.^{[citation needed]}

As with psilocybin and psilocin, ethocybin is a prodrug that is converted into the pharmacologically active compound ethocin in the body by dephosphorylation.^{[citation needed]} This chemical reaction takes place under strongly acidic conditions or enzymatically by phosphatases in the body.

Albert Hofmann was the first to produce this chemical, soon after his discovery of psilocin and psilocybin. It was sold under the code name CEY-39.

As with psilocybin, ethocybin is rapidly dephosphorylated in the body to 4-HO-DET which then acts as a partial agonist at the 5-HT_2A serotonin receptor in the brain where it mimics the effects of serotonin (5-HT).^{[citation needed]}

Terence Kemp McKenna (November 16, 1946 – April 3, 2000) was an American philosopher, psychonaut, researcher, teacher, lecturer and writer on many subjects, such as human consciousness, language, psychedelic drugs, the evolution of civilizations, the origin and end of the universe, alchemy, and extraterrestrial beings.

Terence McKenna grew up in Paonia, Colorado. He was introduced to geology through his uncle and developed a hobby of solitary fossil hunting in the arroyos near his home. From this he developed a deep artistic and scientific appreciation of nature.

At age 16, McKenna moved to Los Altos, California to live with family friends for a year. He finished high school in Lancaster, CA. In 1963, McKenna was introduced to the literary world of psychedelics through The Doors of Perception and Heaven and Hell by Aldous Huxley and certain issues of The Village Voice that talked about psychedelics.

McKenna claimed that one of his early psychedelic experiences with morning glory seeds showed him "that there was something there worth pursuing." In an audio interview Terence Mckenna claims to have started smoking cannabis regularly during the summer following his 17th birthday.