This volume presents two closely related essays by Thomas Nagel: “Gut Feelings and Moral Knowledge” and “Moral Reality and Moral Progress.” Both essays are concerned with moral epistemology and our means of access to moral truth; both are concerned with moral realism and with the resistance to subjectivist and reductionist accounts of morality; and both are concerned with the historical development of moral knowledge. The second essay also proposes an account of the historical development of moral truth, according to which it does not share the timelessness of scientific truth. This is because moral truth must be based on reasons that are accessible to the individuals to whom they apply, and such accessibility depends on historical developments. The result is that only some advances in moral knowledge are discoveries of what has been true all along.