The spirit molecule (DMT / dimethyltryptamine)

Dimethyltryptamine or N,N-Dimethyltryptamine (DMT) is a naturally-occurring tryptamine and psychedelic drug, found not only in many plants, but also in trace amounts in the human body where its natural function is undetermined. Structurally, it is analogous to the neurotransmitter serotonin (5-HT) and other psychedelic tryptamines such as 5-MeO-DMT, bufotenin (5-OH-DMT), and psilocin (4-HO-DMT). DMT is created in small amounts by the human body during normal metabolism.

http://en.wikipedia.org/wiki/Dimethyltryptamine