The concept of death and dying is powerful in the minds of most people. To manage the intense feelings associated with a discussion of death, John Donne personifies death in Death, Be Not Proud, and proceeds to discredit it because, although some may think that death is "mighty and dreadful," he maintains that "thou art not so." Death, in its personified form, is arrogant because it thinks that it is the end of life but Donne points out that it is only "One short sleep." Death cannot get the better of man so Donne wonders why it feels as if it has achieved something when "our best men with thee do go" because, when they die, they simply "Rest (of) their bones."
The arrogance as Death "swell'st thou then" as it thinks that "thou dost overthrow" is unacceptable to Donne and Death is actually the entity that is defeated and overcome every time. It is nothing more than a transition and, whilst everyone must die, "we wake eternally" and therefore we are no longer dead which shows that, in fact, it is Death that "shalt die."