Terence Kemp McKenna was an American ethnobotanist and mystic who advocated the responsible use of naturally occurring psychedelic plants. He spoke and wrote about a variety of subjects, including psychedelic drugs, plant-based entheogens, shamanism, metaphysics, alchemy, language, philosophy, culture, technology, ethnomycology, environmentalism, and the theoretical origins of human consciousness. He was called the "Timothy Leary of the '90s", "one of the leading authorities on the ontological foundations of shamanism", and the "intellectual voice of rave culture".

The I Ching or Yi Jing, usually translated Book of Changes or Classic of Changes, is an ancient Chinese divination text that is among the oldest of the Chinese classics. The I Ching was originally a divination manual in the Western Zhou period (1000–750 BC). Over the course of the Warring States and early imperial periods (500–200 BC), it transformed into a cosmological text with a series of philosophical commentaries known as the "Ten Wings". After becoming part of the Chinese Five Classics in the 2nd century BC, the I Ching was the basis for divination practice for centuries across the Far East and was the subject of scholarly commentary. During the 18th, 19th and 20th centuries, it took on an influential role in Western understanding of East Asian philosophical thought.