First published in 1751, “An Enquiry Concerning the Principles of Morals” by David Hume, the Scottish Enlightenment philosopher, was the enquiry subsequent to his 1748 work “Enquiry Concerning Human Understanding” and is often referred to as “the second Enquiry”. In Hume’s own opinion it was the very best of all his writings. In “An Enquiry Concerning the Principles of Morals”, Hume expands upon his ideas of morality first discussed in his earlier work “A Treatise of Human Nature”. Hume seeks to understand how humans make moral judgments and whether ethics have a basis in objective reality or reason. Hume argues that ethics is fundamentally rooted in sentiment and emotion and that ethics has no meaning apart from human understanding. Rather, whether something is ethical or not depends largely on the feelings that the behavior evokes. Hume also makes the compelling argument that true virtue is based on the natural world and is not dependent on laws or social systems. Instead, the most important and worthy virtues are found in the highest merit that human nature is capable of, such as being merciful, generous, friendly, and benevolent. “An Enquiry Concerning the Principles of Morals” remains an important and thought-provoking masterpiece of philosophy nearly three hundred years later. This edition include a biographical afterword.