Book excerpt: This book deals with Descartes' efforts in his Meditations to discover the first principles of human knowledge, that is, what must be known before anything else can be known. In order for these principles to be first principles, they cannot be conclusions obtained through deductive reasoning. Further, Descartes insists that these first principles cannot be known through the senses, but only through intuition or meditation, our only cognitive faculties for grasping self-evident first principles. This book provides Descartes' reasons for rejecting the senses as the source of these first principles, and offers textual support for the role of intuition and meditation in apprehending the first principles of human knowledge. Although the bulk of the book is largely exegetical in nature, the last chapter proceeds more critically to show the failures of Descartes' approach.