Two archetypes pervade Western thinking on the subject of how reality is best apprehended, archetypes that have their ultimate origin in Plato and Aristotle. For Plato sense data were at best a distraction from knowledge, which was the province of unaided reason. For Aristotle, knowledge consisted in generalizations, but these were derived in the first instance from information gathered from the outside world. These two models of human thinking, termed rationalism and empiricism, respectively, formed the major intellectual legacy of the West down to Descartes and Bacon, who represented, in the seventeenth century, the twin poles of epistemology.