<span>The use of allusion in the title and epigraph of Nectar in a Sieve helps to emphasize the novel’s themes of loss and hope
Nectar in a Sieve alludes to the slow drain of the life force of an individual here on earth. The nectar represents live and the sieve, since it is a sifter/filter, slowly drains the nectar until it falls to the ground and become useless. </span>
It means to give credit to the author and source. It helps in an argument because when you're trying to prove a point, you have to have factual evidence that proves you're right.