An allusion is a term used by literary critics to describe an author referring to elements from literature, the arts, history, or popular culture within a text. Another term sometimes used to describe this phenomenon is "intertextuality". Such references have two purposes. The first is specificity. The word "Penelope" conjures...
up a more specific and vivid image than "loyal wife". The second is compactness. A reference to Sisyphus conveys a painful, dull, endlessly repeated task in a single word.
There are two main classes of allusions used by Faulkner in his novel As I Lay Dying, those to the Bible and to classical literature and mythology, both of which would have been very familiar to his original readers.
A typical example is Peabody describing Addie's "love that passeth understanding" for Jewel, a phrase the echoes the Biblical description of Jesus' love for humanity and is commonly used in liturgical context. In the Anglican Church the following Eucharist, the priest dismisses the congregation with a series of prayers and blessings including the phrase: "THE Peace of God, which passeth all understanding, keep your hearts and minds in the knowledge and love of God."
Cora's statement, "Old Marster will care for me as for ere a sparrow that falls" refers to God seeing even a single sparrow falling in the Bible, specifically Matthew 10:29. Cora frequently quotes from or alludes to the Bible.
The title from the novel is taken from Homer's Odyssey, in which Agamemnon, now in Hades, describes his death, saying: "As I lay dying, the woman with the dog's eyes would not close my eyes as I descended into Hades."