Answer:
The theme of this poem is how Death is not as powerful as it actually believes. It is even a slave to other forces that exist in the universe and even it will also die.
Step-by-step explanation:
The last two lines of this poem say: "One short sleep past, we wake eternally
And death shall be no more; Death, thou shalt die. " This refers to the Christian belief that all believers will awaken from death and live forever. In this way, all credit and power are taken away from Death, who believes itself invincible and powerful.
If all those whom death proudly killed woke up then death itself would know its end.