 The basic structure of Augustine’s ethics is that of ancient eudaimonism (Holte 1962), but he defers happiness to the afterlife and blames the ancient ethicists for their arrogant conviction—resulting from their ignorance of the fallen condition of humankind—that they could reach happiness in this life by philosophical endeavor (De civitate dei 19.4; Wolterstorff 2012; for a more optimistic view, cf. the early De ordine 2.26). He takes it as axiomatic that happiness is the ultimate goal pursued by all human beings (e.g., De beata vita 10; De civitate dei 10.1; De trinitate 13.7, quoting Cicero’s Hortensius; for an interesting discussion of how the desire for happiness relates to our equally natural desires for pleasure and for truth cf. Confessiones 10.29–34; Matthews 2005: 134–145; Menn 2014: 80–95). Happiness or the good life is brought about by the possession of the greatest good in nature that humans can attain and that one cannot lose against one’s will (e.g., lib. arb. 1.10–12; especially in his early work Augustine shares the Stoics’ concern about the self-sufficiency and independence of the wise and happy person, cf. Wetzel 1992, 42–55). This structure Augustine inscribes into his Neoplatonically inspired three-tiered ontological hierarchy (Letter 18.2)  and concludes that the only thing able to fulfil the requirements for the supreme good set by eudaimonism is the immutable God himself. The Supreme Being is also the greatest good; the desire of created being for happiness can only be satisfied by the creator. As Augustine puts in concisely in De beata vita (11): “Happy is he who has God”. Alternative formulations are “enjoyment of God” (De civitate dei 8.8; De trinitate 13.10), “contemplation of God” or “enjoyment of truth” (De libero arbitrio 2.35). To “have” God means in fact to know and, especially, to love God; Augustine therefore interprets Psalm 72:28 (“For me it is good to cling to God”) as a biblical telos formula or definition of the supreme and beatifying good (De civitate dei 10.18; Tornau 2015: 265–266). We are, in other words, happy, wise and virtuous if we turn to or “convert” to God. If we turn away from him and direct our attention and love to the bodies—which are not per se bad, as in Manicheism, but an infinitely lesser good than God—or to ourselves, who are a great good but still subordinate to God, we become miserable, foolish and wicked (Letter 18.2; De libero arbitrio 2.52–54; In Iohannis evangelium tractatus 20.11). Virtue is “love that knows its priorities” (ordo amoris, De civitate dei 15.22) whereas vice or sin perverts the natural order. Just as after the Fall all human beings are inevitably tainted by sin, we need to be purified through faith in order to live well and to restore our ability to know and love God (De diversis quaestionibus 68.3; Cary 2008a: 12–13). Augustine does not discard the intellectual element inherited from the ancient (Socratic) ethical tradition, and his notion of conversion is certainly inspired by Neoplatonist “return” (epistrophe), but Augustine enhances the ethical relevance of conversion and aversion by emphasizing their voluntary character (cf. already De immortalitate animae 11–12).  The element of will or love is also crucial to the distinction between “enjoyment” (frui) and “use” (uti) that is first fully developed in De doctrina christiana, bk. 1 (c. 396) and remains basic for his ethical thought. Following the ancient insight that we pursue some goods for their own sake and others for the sake of other and greater goods, Augustine states that to “enjoy” a thing means to cling to it with love for its own sake whereas to “use” it means to love it for the sake of another thing which we want to enjoy. We love absolutely only what we enjoy, whereas our love for things we use is relative and even instrumental (De doctrina christiana 1.4). The only proper object of enjoyment is God (cf. De civitate dei 8.8 where the same view is attributed to the Platonists). Wickedness and confusion of the moral order results from a reversal of use and enjoyment, when we want to enjoy what we ought to use (all created things, e.g., wealth, bodies or ourselves) and to use what we ought to enjoy (this probably refers to the “carnal” understanding of religion of which Augustine often accuses the Jews). An obvious problem of this system is the categorization of the biblically prescribed love of the neighbor. Are we to enjoy our neighbor or to use her? Whereas natural moral intuition suggests the former, Augustine’s systematic seems to require the latter. The problem is inherited from ancient eudaimonism, where it takes some philosophical effort to reconcile the intuition that concern for others is morally relevant with the assumption that ethics is primarily about the virtue and happiness of the individual. Augustine is aware of the problem and gives a differentiated answer. In De doctrina christiana (1.20–21) he somewhat tentatively suggests that to love our neighbor means to use him, not because he is merely instrumental to our happiness but because we are enjoined to love him as ourselves and because we love ourselves rightly only if we refer our self-love to our desire to enjoy God. Love of the neighbor thus means to desire his true happiness in the same way as we desire our own. In substance, this remains Augustine’s view also in his later work (cf., e.g., In epistulam Iohannis ad Parthos tractatus decem 1.9), but he then prefers to avoid the counter-intuitive and potentially misleading talk about “using” fellow humans and replaces it by a description of fraternal love as “mutual enjoyment in God” (e.g., De trinitate 9.13; cf. already De doctrina christiana 1.35; 3.16; Rist 1994: 159–168; O’Donovan 1980: 32–36; 112–136). “In God” is presumably added to prevent the misunderstanding that we are to enjoy the neighbor “in herself” or “in ourselves” without reference to God. This would mean that we expect our true happiness from her, which no human can give; the result of this misdirection would be extreme misery in the case of the neighbor’s loss (cf. Confessiones 4.9–11 on Augustine’s excessive grief after the death of his friend; Nawar 2014).