Perceptual experience is often conceived as a foundation for human knowledge. Many philosophers hold that experience can serve this role only because it has certain non-conceptual aspects. This view raises problems that have taken many forms throughout the history of philosophy. Given that human knowledge is conceptual, how can the non-conceptual aspects of experience be of relevance to it? And if they cannot, how can experience be a foundation for knowledge? The essays collected in this volume explore these and related issues in a wide variety of ways. The discussions draw on sources ranging from Aristotle and Plotinus through Kant to contemporary philosophers such as John McDowell and Donald Davidson. The book will appeal to philosophers interested in epistemology and the philosophy of mind, and to anyone concerned with the nature of rationality. The range of approaches discussed should make it valuable to philosophers of differing persuasions.