In chapter 9 of this volume, we saw that imagination was central not just to Descartes' mathematics and physics, but also to his conceptions of method, problem solving, and living a fully human life. Contrary to what might appear from a cursory look at his works, Descartes did not so much reject previous theories of imagination as radicalize them. He did not abandon the old Aristotelian and scholastic dictum that there is no thinking without phantasm or imagining, but instead determined that it was for the most part true -although the "I" recognized in the being of the radical doubter and the God recognized as the existing cause of the doubter and all his ideas ultimately transcend imagining. Analytic geometry and the natural sciences based on it were projections of directed, accurate imagining within a comprehensively imagined space. The human passions and emotions, long considered as alien to reason, were instead fundamental consequences of the embodiment of the willing and perceiving res cogitans in a psychophysiological network of nerves, animal spirits, and brain. This network, in its turn, was the basic element of imagination. Imagination was thus embodied reason. Descartes' innovative use of "idea," foundational for all early modern philosophizing, was patterned on an analogy according to which the ideas, the forms of thought of the human mind, were in essence like the products of God's imagination -his phantasia -despite the fact that God, being perfectly incorporeal, has no imagination.
The appropriation of Descartes' philosophy by the next generation of Cartesians brought a shift away from this center of gravity in imagination. The Port-Royal Logic of Arnauld and Nicole insisted on the radical differentiation of ideas from images, while Malebranche argued that imagination, however necessary for living and however useful in mathematics and science, was a prime source of human error and even possibly the medium that transmitted original sin. The union of body and soul was, at any rate, merely temporary. In this corporeal world we can rise to the level of seeing ideas in God; in the next life our intellect will not be obscured by the body.
The question of the ontological and epistemological status of ideas and their difference from images was the chief legacy of Cartesianism to the following generations of philosophers. But it is arguable that Descartes' major concern was less the ontologicalepistemological status of the image than what the human mind does with and to images: that is, imagination as a fundamental psychological and anthropological operation. Philosophers after Descartes tended to assume that the operations of intellect and