One of the legacies of the combined influences of ancient Greek philosophy and Judeo-Christian belief is the use of light as a basis of various figurative devices within discussions of learning and thought. In fact with its prominent uses in such texts as the first chapter of the Book of Genesis (e.g., “Let there be light …”) and throughout Plato’s Republic (in particular in his cave allegory), by Descartes’ time it had become the metaphor of choice around matters of knowledge and knowing.