"Knowing how we know" is the subject of Tree of Knowledge. Its authors present a new view of cognition that has important social and ethical implications, for, they assert, the only world we humans can have is the one we create together through the actions of our coexistence. Written for a general audience as well as for students, scholars, and scientists and abundantly illustrated with examples from biology, linguistics, and new social and cultural phenomena, this revised edition includes a new afterword by Dr. Varela, in which he discusses the effect Tree of Knowledge has had in the years since its first publication.