The seventeenth century saw a fundamental shift in our ways of thinking about ourselves and the universe. The reassuring medieval view of an earth-centred cosmos designed expressly for the benefit of mankind had been steadily eroded; yet at the same time there emerged a new optimism about the possibility of developing a clear and comprehensive account of the workings of the universe, together with a determination to penetrate the nature of the human mind and its relation to the material world. Against this background John Cottingham traces the attempts of the three great rationalist philosophers - Descartes, Spinoza, and Leibniz - to come to terms with man's new role in nature and to devise new systems of philosophy that would provide a unified understanding of reality. He aims to show how closely their ideas are related, and analyses their ways of tackling such central issues as the relation between mind and body, the nature of substance, and the way to achieve a free and fulfilled Human life. He engages with their ideas in a vigorously critical way, and in so doing reveals their capacity to throw light on major philosophical topics which are still very much alive today.