FLOW EXPERIENCE. All major world religions, as well as most sects and tribal cults, are said to produce on occasion, among their faithful, states of ecstasy or altered states of consciousness. Such experiences constitute for many believers one of the main attractions of religion, if not a proof of its ability to mediate the supernatural. In cults and sects such experiences are often induced by chemical substances ingested in ritual contexts; by fasting; by various hypnotic trances, or by what Émile Durkheim called "collective effervescence," a condition engineered by rhythmic music, dance, and ritual movements.

Remnants of such direct sensory means for inducing altered experiential states can still be found in the major religions. The use of music, chanting, lighting, and scent in liturgy and of fasting and ritual feasting clearly derive from earlier methods for producing ecstasy. But the great religious traditions have become gradually...