MYSTICISM [FIRST EDITION]. No definition could be both meaningful and sufficiently comprehensive to include all experiences that, at some point or other, have been described as "mystical." In 1899 Dean W. R. Inge listed twenty-five definitions. Since then the study of world religions has considerably expanded, and new, allegedly mystical cults have sprung up everywhere. The etymological lineage of the term provides little assistance in formulating an unambiguous definition. In the Greek mystery cults, muein ("to remain silent") probably referred to the secrecy of the initiation rites. But later, especially in Neoplatonic theory, the "mystical" silence came to mean wordless contemplation. Even this "contemplation" does not coincide with our own usage of that term, since theōria denotes speculative knowledge as well as what we call contemplation.

Nor does the early Christian term mustikos correspond to our present understanding, since it referred to the spiritual...