The song is built on a single grammatical shape, and it is the shape of a trap. X, who can fix anything, fixes Y. But the moment X itself is hurt, there is nobody left. The monsoon can put out fires, but there is no rain for the monsoon's own fire. Spring can revive the garden, but not the garden that died in spring. The rhyme scheme enforces it: every couplet ends with the same helpless question, use kaun, who can do that for it.
The third passage is where the song stops being a weather report and becomes a film. Humse mat puchho kaise, mandir tuta sapnon ka: don't ask us how, the temple of dreams broke. And then the line that explains the whole film: this is not a story of outsiders, it is a story of our own people. Kissa apnon ka. A stranger's blow, a friend can soothe. But the wound dealt by a manmeet, a soul-friend, the one closest, nobody can erase. Amar Prem is the story of a courtesan and the lonely businessman who loves her, and the wound that has no remedy in this song is the film's own: the one a loved one deals, out of love or duty itself.
The fourth passage is the one that left the theatre with the audience. Na jaane kya ho jaata, jaane hum kya kar jaate. Who knows what would happen, who knows what we would do. The line trails off into the chorus of the drinking song inside this song: we drink, so we are alive. We do not drink, so we die. The sorrow it is describing has no name, and the stanza refuses to give it one.
The last passage brings in the sea and the boatman, and it is the grimmest of the set. Even the storm has an excuse, the waves have no fault, the fault is somebody else's. But the boat in mid-stream, in the majdhaar, needs the boatman to land it, and if the boatman himself sinks the boat, who saves anyone. The song has arrived at its real subject: the only person who can destroy you is the one you trusted with the boat.
Kishore Kumar's delivery of it, riding R.D. Burman's tune, made it one of the most loved songs of the decade. The film used it as its anthem of rain and loneliness, and the recording people mean is the one from the film.