This classic work by William Paley was one of the most popular books in England and America in the early nineteenth century. Its significance lies in the fact that it marks an important point at which eighteenth century 'whiggism' began to be transformed into nineteenth century 'liberalism'. First published in 1785, Paley's Principles of Moral and Political Philosophy was originally based on his Cambridge lectures of 1766-1776. It was designed for instructional purposes and was almost immediately adopted as a required text for all undergraduates at Cambridge. The great popularity of Paley's Principles is perhaps due in part to the author's remarkable gift for clear exposition. Even today, this work is very readable and easily comprehended. But the popularity of the book also reflected the fact that Paley expressed some of the leading scientific, theological, and ethical ideas of his time and place. In this respect, Paley's great classic provides valuable insight into the Anglo-American mind of the early nineteenth century and helps us better understand the thinking processes and evolving concepts of liberty and virtue that were displacing the old 'whiggism' of the preceding century. This clearly and engagingly written book is designed for instructional purpose, and was adopted as a required text for all undergraduates at Cambridge. It is an excellent example of Enlightenment philosophy and played a seminal role in the dissemination of theological utilitarian in England.