Theoretical work de Certau, Michel (1986). "Chapter 6: Mystic Speech". In Heterologies: Discourse on the Other. Translated by Brian Massumi. Pp. 80-100. Also the Foreword, vii-xxi. Manchester, UK: Manchester University Press. This chapter examines the nature of mystic speech in Europe several centuries ago. Sells, Michael (1994). Mystical Languages of Unsaying. Chicago: The University of Chicago Press. Table of contents, 1-13 (notes 219-225), 206-217 (notes 302-3). This text attempts to interpret the nature of negative rhetoric utilized by mystical religious movements. Loy, David (1988). Nonduality: A Study in Comparative Philosophy. New Haven: Yale University Press. Pp. table of contents, 1-14, 178-186, 292-304. This is a comparative attempt to talk about the significance of "nonduality" in various systems of thought and practice.