The following secondary sources were useful in placing the teachings of the Pali Canon in their historical context, both social and intellectual:
Jayatilleke, K. N. Early Buddhist Theory of Knowledge. London: George Allen & Unwin Ltd., 1963.
Warder, A. K. Indian Buddhism, 2d. ed. Delhi: Motilal Banarsidass, 1980.
__________. Outline of Indian Philosophy. Delhi: Motilal Banarsidass, 1971.
__________. "Prologomena to a History of Indian Science" in New Paths in Buddhist Research, edited by A. K. Warder. Durham, N. C.: Acorn Press, 1985.
Weiss, Mitchell G. "Caraka Samhita on the Doctrine of Karma" in Karma and Rebirth in Classical Indian Traditions, edited by Wendy Doniger O'Flaherty. Berkeley: University of California Press, 1980.
Two books by Ernest G. McClain -- The Myth of Invariance andThe Pythagorean Plato (New York: Nicholas-Hays, 1976 and 1978), dealing with the influence of music theory on the thought of ancient civilations, ranging from Greece to India -- inspired me to look for traces of musical theory in the teachings of the Pali Canon. The following books were useful in my research into ancient Indian music theory and the role that the word nimitta (theme) played in that theory:
Bhattacharya, Arun. A Treatise of Ancient Hindu Music. Columbia, Mo.: South Asian Books, 1978.
Warder, A. K. Indian Kavya Literature. Volume One: Literary Criticism. Delhi: Motilal Banarsidass, 1989.
__________. Pali Metre. London: Pali Text Society, 1967.