This volume, which grew out of a 1995 NEH seminar on the Rationalists, presents nineteen previously unpublished papers on the work of Descartes, Spinoza, and Leibniz. These three philosophers are the most important representatives of the 17th and 18th century movement known as rationalism, which can be characterized by the idea that knowledge can be acquired a priori, without sensory experience, from pure thought or reason. Particularly in epistemology and metaphysics, their work has remained at the centre of philosophical interest. The volume is thematically organized into three Parts: Matter and Substance, Freedom and Necessity, and Mind and Consciousness.