"Thanks to the simplicity of its vocabulary and structure, it was the first of his formulae to be noticed [(le première formule qui a retenu toute l'attention)] and is constantly repeated. Forgetting that it is part of an instruction on [fraternal] charity, some have invoked it, be it in favor of laxist theses, be it in support of situation ethics [(la morale de situation [or situationism (Bourke)])]. Taking an uncritical stand on its first word, [some] authors have identified dilection and [the] love of God, though it is [quite] clear that Augustine has here only fraternal love in mind directly. . . .
"Gally claims that the anti-Donatist controversy is the context in which one must read the phrase and that it 'is [therefore] neither more nor less than a justification of measures of repression against Donatism'.
"This rigorous study merits every consideration, but insists too much on the most paradoxical of the applications that can be made of it [(de la maxime)] and appears [therefore] too unilateral. Poque in fact shows that ep. Jo. tr. 7 and 8 were preached on the same Easter Saturday, and that they both make reference to the reading of a long passage from Mt 5 and 6 (cf. ep. Jo. tr. 7.1; 8.2, 4). Moreover, Augustine reveals that he intends to complete on that day the moral instruction of the neophytes by addressing them on the subject of charity.
"Reread thus in its immediate context and in the light of the givens preceding, it becomes obvious that the formula was adopted by moderns who, [by] transform[ing] it into a slogan, [gave it] an exaggerated importance [(la formule a reçu des modernes qui en ont fait un slogan une importance exagérée)]. It has absolutely nothing in any case [to do] with [(n'a absolument rien en tout cas d')] an appeal to the laxism that would open the door to fantasies [(fantaisies)] of every sort, [but] on the contrary is perfectly integrated into an instruction on fraternal charity, its value and its demands, its attitudes and its obligations.
"Augustine proclaims once again thereby the primacy of the charity that must be found at the root of all Christian action, but adds immediately a clarification of the utmost importance for practice: this same charity can in fact inspire in the heart of the faithful behaviors as different as mercy or severity, silence or protestation, correction or indulgence, [behaviors] that must, all of them, be dictated by the true and generous love of neighbor, and take always persons, situations, and times into account."
Marie-François Berrouard, "Dilege et quod uis fac," Augustinus-Lexikon, ed. Mayer, vol. 2, fasc. 3/4 (Basel: Schwabe & Co. AG, 1999), cols. 453-455.
Incorporate thoroughly here also Giles Constable, "'Love and do what you will': the medieval history of an Augustinian precept" (1996), in The Morton W. Bloomfield lectures, 1989-2005, ed. Daniel Donoghue, James Simpson, and Nicholas Watson (Kalamazoo, MI: Medieval Institute Publications, Western Michigan University, 2010), 65-93, among other works of scholarship. Constable begins by citing (as does Berrouard), in addition to the commentary on 1 John, Serm. Frang. V, 3 (PL 46, col. 985 and Sermones post Maurinos reperti, Miscellanea agostiniana 1, ed. Germain Morin (Rome, 1930), p. 214) on Gal 6:1:
And if you speak out, love within [intus], you exhort; you coax; you chide; you rage; dilige et quicquid uis fac. For a father does not hate his son; and yet a father, if there is need, beats his son; he inflicts pain in order to protect salvation.Here is the latter in the 1992 translation of Edmund Hill:
"So, brothers and sisters, if a man has been caught out in some wrongdoing, you who are spiritual, whoever you are that are spiritual, instruct such a one in a spirit of mildness (Gal. 6:1). And if you shout at him, love him inwardly; you may urge, wheedle, rebuke, rage; love, and do whatever you wish. A father, after all, doesn’t hate his son; and yet if necessary a father gives his son a whipping; he inflicts pain, to ensure well-being. So that’s the meaning of in a spirit of mildness. You see, if a man has been caught out in some wrongdoing, and you say, ‘It’s no business of mine,’ and I say to you, ‘Why isn’t it your business?’ and you answer me, ‘Because each one will bear his own burden’; then I will answer you, ‘Why, you certainly have been willing to hear and understand Bear one another’s burdens!’
"So then, if a man has been caught out in some wrongdoing, you who are spiritual instruct such a one in a spirit of mildness. He, certainly, is going to give an account of his own sin, because each one will carry his own burden; but you, if you neglect his wound, are going to have a bad account to give of your sin of negligence. . . .
". . . do not ignore and neglect each other’s sins. Reprimand those who have confidence enough in you to take it; give a friendly warning to those who don’t trust you enough to take a reprimand; and should it come to that, pray, beg someone not to sin" (WSA III/5 (New Rochelle, NY: New City Press, 1992), pp. 182-183).
This caught my eye in part because I had recently watched Robert Gagnon's demolition of Walter Wink's use of this against him in the opening minutes of the Gagnon presentation located here (you do have to move from there to the Gagnon presentation specifically).