That said, ayahuasca will never be your mom’s Ginkgo biloba, either. The word itself, from the western Amazon’s Quechua language, means "vine of the soul" or "vine of the dead." It refers both to a woody liana whose bark goes into the boiled brew and to the tonic’s reputation for opening a door into "the sacred dimension of reality." Today, ayahuasca has emerged from the shrinking Amazon forest into the wider global imagination. Some say it has a message for the modern world from the planetary mind: It’s time to clean up our act. Skeptics think what ayahuasca enthusiasts really hear is the echo of their own clamor for spiritual novelty. Meanwhile, McKenna and others are straining the stuff through the fine mesh of science, trying to understand how it actually works. They are dealing with some very weird molecules that seem to know us better than we know ourselves. XFONT Scientists generally refer to psychedelic drugs as hallucinogens, though most do not induce hallucinations in a scientific sense. Scholars of religion often call them entheogens, from the term "god within." No one calls them narratogens, but that may be the most accurate term: The one thing they surely do is generate stories. For decades, ayahuasca was the stuff of legend for various wandering scientists and dharma bums, from Harvard’s famed ethnobotanist Richard Evans Schultes to beat poet Allen Ginsberg. In 1971 Dennis and his older brother, Terence McKenna, the influential psychedelic philosopher and raconteur, hit the trail themselves. Their trip inspired a co-written book, The Invisible Landscape (Seabury, 1975), which contains some early thoughts by Dennis on how the "tryptamine" hallucinogens like aya-huasca and psilocybin might affect the mind. Today, a doctorate from the University of British Columbia and a revolution in neuroscience later, Dennis says he mostly rejects those theories. Terence, who died last year of a brain tumor at age 53, told their story again in True Hallucinations (HarperCollins, 1993).These quest narratives once shaped what most Americans knew about ayahuasca, which wasn’t much. Thanks partly to the ease of modern travel, including ayahuasca tours to the Amazon, that has changed. A bigger factor in the growing awareness of ayahuasca is all the traffic going the other way. The Amazon region’s cultural patterns have been severely disrupted in recent decades, along with the rich tropical ecosystems that shaped them. Rubber plantations, mining operations, logging, and oil exploration have all helped drive tribal people out of the forest and into South America’s swelling urban centers. Ayahuasca went with them.