John Donne’s poem, “Death, be not proud,” focuses on death as a transitory state between life and what comes after life. In the poem, the speaker personifies and then chastises death, explaining that it holds no real power despite what others might attribute to it.
To show death’s lack of true power, the speaker equates death with sleep, specifically pointing out that sleep is a temporary state:
One short sleep past, we wake eternally
And death shall be no more; Death, thou shalt die.
The speaker is expressing the idea that death is only a period of unconsciousness before a person, or maybe better a soul, awakens to an eternal life.
The sleep metaphor is intended to help the reader understand that the finality of death is, according to the speaker, illusory. Further, by equating death with sleep, the speaker attempts to diminish death by referencing other causes of sleep, thereby putting death on the same footing as things such as poppies and charms.
It is this diminished and contextualized personification of death that the speaker admonishes to “be not proud.” In the speaker’s worldview, death is nothing save a period of rest before the afterlife.