The second line of the poem "And the great star early droop'd ..." establishes the allusion to Lincoln. The blooming of the lilacs in April, the same month in which Lincoln was assassinated, serves as Whitman's yearly reminder of Lincoln's death. This star is historically the planet Venus, which was low in the sky at the time Whitman wrote his poem.
Peter De Vries' novel The Blood of the Lamb uses motivs from Whitman's poem, including the brown thrush with its "unendurable" song, and the association of lilacs with death. The main character's daughter is also named Carol, possibly an allusion to the brown-grey thrush's "Carol of Death."
The popularity of the poem has often made it subject to parody and satire.