In an age of intellectual exploration Thomas Hobbes can be ranked among the Drakes and Magellans of the mind. New ideas and discoveries in mathematics, astronomy, medicine and analytical thinking. In philosophy and politics, as in his inquiries into human thought, senses, and nature, he carted whole new coastlines. Hobbes is often called the father of modern analytical philosophy: he can also claim to be the father of modern psychology. This study by Richard Peters, which first appeared ten years ago in the Pelican Philosophy Series, is now reissued in Peregrines as one of the best modern studies of an English thinker whose masterpiece, Leviathan, written against the seething intellectual and political background of the seventeenth century, can still be reckoned among the great books in philosophy.