In Act II scene 3 of Othello Cassio, who has just disgraced himself by brawling when drunk, inveighs against wine: "Every inordinate cup is unblest, and the ingredience is a devil." However Iago — who hates Cassio because he has been promoted above him and because he is a Florentine rather than a Venetian, and who has tempted Cassio into drunkenness precisely to discredit him with the Moor — will hear none of this: "Come, come, good wine is a good familiar creature, if it be well used: exclaim no more against it." Which man is right?
Their exchange comes towards the end of a scene in which Shakespeare dramatises the process of intoxication in a wonderfully accelerated form. Cassio, who admits to having "very poor and unhappy brains for drinking", wants to have an early night, but Iago is adamant that Cassio must attend the drinking party Iago has arranged to celebrate Othello's wedding night:
Well: happiness to their sheets! Come, lieutenant, I have a stoup of wine, and here without are a brace of Cyprus gallants that would fain have a measure to the health of black Othello.
Cassio eventually agrees to take part in Iago's "night of revels" ("I'll do't, but it dislikes me"), and goes off stage to bring in the gallants that Iago has invited. At this point Iago — switching from prose to verse, and left alone on stage — reveals his plan:
If I can fasten but one cup upon him,
With that which he hath drunk tonight
He'll be as full of quarrel and offence
As my young mistress' dog. Now my sick
Whom love hath turned almost the wrong
To Desdemona hath tonight caroused
Potations pottle-deep, and he's to watch.
Three else of Cyprus, noble swelling spirits
That hold their honours in a wary distance,
The very elements of this warlike isle,
Have I tonight flustered with flowing cups,
And the watch too. Now 'mongst this flock
Am I to put our Cassio in some action
That may offend the isle.