In September 1980, during my participation in Projecto Flora Amazonica expedition to Acre, Brazil, my colleagues Bruce W. Nelson, Carlos Alberdo Cid Ferreira, Stuart R. Lowrie, and I, visited a small colony of zealots who augmented their Christian fervor by imbibing a mixture of approximately equal parts of an aqueous extract of the bark of Banisteriopsis caapi and the leaves of a rubiaceous plant, Psychotria viridis Ruiz et Pavon, the drink called by cult members "Santo Daime," a name indicative of its perceived sacred properties.