This particular metaphorical device is called “personification,” where an abstraction is given physical properties to compare the abstraction with a visible, imaginable action. “Just like a bird flies up to the sky, my words fly up to heaven. But because the words are hollow and empty, the thoughts of the speaker do not fly up, but remain on earth and are not received (by a Deity).” It is sometimes called an “animation”; technically, a personification must give human qualities to an inanimate object: “The sun smiled at me today.” These words, a rhyming couplet that gives closure to Hamlet’s soliloquy (another example of Shakespeare’s creative genius, to have someone else’s lines close Hamlet’s soliloquy), are spoken after the king’s prayers, outwardly of penitence. He is praying as Hamlet watches him and decides not to kill him while he prays, because the King’s soul would go to heaven. But the King rises, realizing that the insincerity of his prayers makes them useless—he still is greedy for power and is not really remorseful.