Alasdair MacIntyre, 2007, After Virtue: A Study in Moral Theory, Third Edition, University of Notre Dame Press. Prologue: After Virtue after a Quarter of Century.
I had now learned from Aquinas that my attempt to provide an account of the human good purely in social terms, in terms of practices, traditions, and the narrative unity of human lives, was bound to be inadequate until I had provided it with a metaphysical grounding. It is only because human beings have an end towards which they are directed by reason of their specific nature, that practices, traditions, and the like are able to function as they do. So I discovered that I had, without realizing it, presupposed the truth of something very close to the account of the concept of good that Aquinas gives in question 5 in the first part of the Summa Theologiae