William Ames on Eliot's use of lilacs in The Waste Land:
Whitman, having the same habit as Milton of writing out long explanations and lists, would seem an unlikely choice for Eliot to include in his poems, but there is evidence which suggests that he was. Eliot wrote primarily in free verse, which in itself denotes Whitman, but the use of lilacs in the first stanza of The Waste Land suggests more: "April is the cruellest month, breeding / Lilacs out of the dead land, mixing . . ." The flower that most people of the early 1920s would have picked is the poppy, from John McCrae's "In Flanders Fields." (McCrae, 85) The deforestation of land in World War I gave enough sunlight to germinate the seeds of poppies which otherwise would not have sprouted. The fact that poppies grew in quantity, feeding on the putrefaction of dead soldiers, was common knowledge, but if Eliot wanted an allusion to flowers, he had one in McCrae. Eliot chooses instead to use the lilac, which grows quickly, but not nearly as fast as the poppy. Lilacs did not grow in abundance on the former battlefields, but they were popularized by Walt Whitman after the death of Abraham Lincoln in "When Lilacs Last in the Dooryard Bloom'd"The imagery of the lilac symbolizes hope for the future. The cyclic nature of the lilac's bloom each year gives the speaker peace, even in the face of heart-breaking anguish. Eliot deliberately recalls this sentiment and then alters it to become his own. He makes use of the allusion and the power it has, but for his own purposes. Whitman, like Milton, gives Eliot the basis to build a new form on, but also something to react against, so that the newness is appreciated as individual talent. Eliot uses the best techniques and the history of author's previous contributions to improve and to create his own style of writing.
When lilacs last in the dooryard bloom'd,
And the great star early droop'd in the western sky in the night,
I mourn'd, and yet shall mourn with ever-returning spring.
Ever-returning spring, trinity sure to me you bring,
Lilac blooming perennial and drooping star in the west,
And thought of him I love.
The topic of Ames essay is summed-up pretty well in his opening statement:
T.S. Eliot's beliefs, as stated in "Tradition and the Individual Talent" led to the creation of a new poetic form in The Waste Land.