What literary device is prominent in Hamlet's phrase "perchance to dream"?

The phrase "perchance to dream" from Hamlet employs metaphor as a prominent literary device. A metaphor makes a comparison between two unlike things without using "like" or "as," allowing readers to understand a concept or idea in a deeper, more relatable way. In this context, Hamlet is contemplating the nature of dreams and existence, equating death with a long sleep wherein dreams may occur, thus exploring profound themes about life, death, and what lies beyond in a figurative manner. This layered meaning prompts readers to consider not just the act of sleeping but the existential implications it holds, making the metaphor central to the line's significance in the play.

While other choices like alliteration (the repetition of initial consonant sounds), personification (attributing human characteristics to non-human entities), and oxymoron (a figure of speech that combines contradictory terms) each serve important roles in literature, they do not capture the essence of Hamlet's philosophical musings in this phrase as effectively as metaphor does.