Act 5, scene 2 is the final scene of the play. In it, the audience encounters the title character standing over his sleeping wife, preparing to murder her. A short soliloquy reveals that he is emotionally torn about the horrible act. His misgivings are revealed through two metaphors. The first metaphor compares Desdemona to a light:
Put out the light, and then put out the light.
If I quench thee, thou flaming minister,
I can again thy former light restore,
Should I repent me; but once put out thy light,
... I know not where is that Promethean heat
That can thy light relume.
In other words, he is about to snuff out the light and his wife's life. The former he can easily relight. The latter he realizes that he cannot. Once he kills his wife, she is gone forever. The second metaphor underscores this tragic reality:
When I have pluck'd the rose,
I cannot give it vital growth again,
It must needs wither; I'll smell it on the tree.
This metaphor works on a number of levels. Desdemona is beautiful like a rose, and as he kneels to "smell it," that is, to kiss her, he is struck even more by her beauty. But his beautiful wife is like a rose in another sense. Once a rose is "pluck'd," it cannot grow again, but "must ... wither." Desdemona cannot be brought back to life after she dies.
With these two metaphors, Othello, convinced that his wife has been unfaithful, ponders the finality of the act he is about to commit. Soon after she wakes, he confronts her with the "evidence" that she has been carrying on an affair with Michael Cassio, and despite her denials and his own initial internal struggle, he suffocates her to death in her own bed.