On the special status of this ghazal, see {485,1}.
Here's a fine example of an 'A,B' verse: two brief, semantically independent statements, for which we have to make our own decision about the 'connection' between them. They might both be describing the same situation (the speaker could be reporting his symptoms to a friend, or even a physician). Or one of them might be the cause of the other: If (1) is the cause and (2) the effect, then the lover's repeatedly going to the beloved's door (and, apparently, never being admitted) causes him to become agitated. If (2) is the cause and (1) is the effect, then it's the lover's agitation that causes him to go again and again to the beloved's door.
In either case the speaker seems barely to know what's going on. He's agitated, anxious, unable to settle down. An ordinary person in such a state would tap his foot or twist his fingers or automatically, instinctively, pace the floor. But the lover has his own form of agitation: he automatically, instinctively, helplessly, keeps going to the beloved's door.
That initial baar baar makes a powerful beginning; it almost sounds like someone pounding on a door. But does the lover actually knock, and seek admission there? And does that door ever open to him? The verse gives us no clue.
