After this virtuoso redescription of dissipation as wise husbandry, Falstaff draws the conclusion: "If I had a thousand sons, the first human principle I would teach them should be to forswear thin potations, and to addict themselves to sack." "Addict" here does not primarily carry its modern meaning of "become physically dependent on".  In the 1590s its connotations were far less degrading, for it chiefly meant to sign up to something, or formally to associate yourself with something. It tended to be used of principled commitments (such as religion), rather than accidentally or viciously acquired cravings and dependencies. This choice of word, which modern ears may easily mishear as an unexpected moment of candour  by Falstaff concerning the abjection that drink can lead to, is in fact the final stroke in Falstaff's brilliant dressing-up of habitual drunkenness in the garb of enlightened wisdom, careful prudence and sober principle.

Part of the great joke here, of course, is that this encomium on the bodily and psychological benefits of excessive drinking has been given to a man whose urine (as we know from the opening scenes of the play) shows traces of more diseases than his doctor is acquainted with, and whose girth announces him as (in Hal's words) "that bolting-hutch of beastliness, that swollen parcel of dropsies, that huge bombard of sack, that stuffed cloakbag of guts, that roasted Manningtree ox with the pudding in his belly".  

But the unlikeliness of the spokesman for this positive view of drinking should not lead us to the conclusion that, for Shakespeare's audiences, what Falstaff was saying was self-evidently rubbish. If Falstaff's view of drinking were merely incredible, the point of the joke would be entirely lost — the impudence lies in the speaker, not the doctrine.  In fact, Falstaff's ideas on drink, and the models of the mind and the body which inform it, open a window on to early modern attitudes to those topics which were very durable. As late as 1795, John Wright in his Essay on Wines would praise the effects of port in terms clearly close to those used by Falstaff: "good wine now and then mends the mind, prevents peevishness, and gives a gentle fill up to sluggish circulation or nervous torpor."

Modern medical science wishes increasingly to persuade us that wine, in common with other forms of alcohol, is nothing more than a powerful cell poison. But for many centuries men have thought about wine in more subtle and more positive ways than this, and it would be arrogance to say that they were simply mistaken. In fact, it would be even worse than arrogance — it would be to associate yourself with Prince John, rather than with Falstaff.