An epigraph is a short quotation or phrase usually found at the beginning of a book or chapter that sets the tone or theme for what follows. It provides context or expresses a key idea related to the main content of the text. Full definition
Readers are fiercely competing to be the most fabulously irreverent as they punctuate Americans» First Amendment rights in response to professor Eugene Volokh's call for epigraphs for his textbook on the First Amendment. (legalblogwatch.typepad.com)
And in Atwood's sly juxtaposition of epigraphs from Genesis and Swift's «A Modest Proposal,» another bomb drops: the Handmaid idea originated with a woman and is connectable, via Swift, with cannibalism. (religion-online.org)
In my opinion, when it comes to very minimal excerpts (which are usually the case with epigraphs), it's about how cautious you want to be, as well as how firm a grasp you have on what constitutes fair use. (janefriedman.com)