"Rene Descartes is often called the 'Father of Modern Philosophy.' The profound controversies that his doctrines have engendered are alone sufficient to establish his eminence. Yet if he is to be paid a due respect, it is necessary to understand him on his own terms- to distinguish his doctrines from myriad notions labeled 'Cartesian.' The quest for certainty may be a constitutional imperative for every philosopher; in the case of Descartes it was an acknowledged passion. Thus there is no more fitting approach to him than to study seriously his claims to having attained certainty regarding what he took to be the questions of metaphysics, namely, the questions of the existence of God and of the nature of the human mind." - from the Preface.