Epigraphs are like little appetizers to the great entrée of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
1) "Dream when the day is thru,
Dream and they might come true,
Things never are as bad as they seem,
So dream, dream, dream."
— Johnny Mercer,
from "Dream," a popular song in the 1940s.
2) "the rare occurrence of the expected…"
— William Carlos Williams,
from "At Kenneth Burke's Place" 1946
What's up with the epigraph?
In looking at these two (very different) epigraphs, it's helpful to remember that American Pastoral is very much a novel about writing and the writing process. Together the two quotes tell us something about Philip Roth's writing process and about the writing process of Nathan Zuckerman. Zuckerman, of course, is Roth's fictional alter-ego, the writer who dreams the story of Swede Levov, the tragic hero of the novel.
You've probably heard Mercer's classic "Dream" —it's in a bunch of soundtracks—and listening to it again will probably help you feel the mood the song sends Zuckerman into when he hears it at his 45th high school reunion.
If you don't fancy listening to it, at least check out the lyrics. Really dreamy and nostalgic stuff, isn't it? Just the thing to send Zuckerman on a journey of the imagination.
The lines also sound like advice to the Swede. When life is too hard, you just have to dream. From the time Merry drops the bomb to the end of the Labor Day dinner party in 1973, things seem to keep getting worse.
When Zuckerman meets the Swede at Vincent's in 1995 things are worse than they seem, which Zuckerman finds out from Jerry just a few months later. The Swede now has a new life and what looks like a wonderful relationship with his sons. But not only is he about to die from cancer, he's also still haunted by his lost life with Merry and Dawn. Since he's about to die, the lyrics seem pretty dang ironic.
As noted, "Dream" isn't just in the epigraph, but is also in the story. It acts as a catalyst to Zuckerman's imagination. This might alert us that popular culture is a big part of both Zuckerman and Roth's artist toolbox—just check out the number of pop cultural "Shout Outs" American Pastoral makes.
Roth and Zuckerman draw heavily on literary culture as well, which brings us to the second part of the epigraph, the fragment from the poem "At Kenneth Burke's Place" by celebrated author, poet, and physician William Carlos Williams.
Kenneth Burke was Williams' friend and another influential writer and poet, perhaps most famous for his way of looking at fiction, called "dramatism". Dramatism looks at characters in a book like actors in a drama and seeks to dramatize them by exploring their motivations, something like what Zuckerman does when he explores Merry's possible motivations for bombing buildings.
All that aside, the lines from the poem say what the novel itself says in a thousand ways, a thousand times: it's rare that anything in life is as we expect it to be—things, and especially people, are rarely (if ever!) what or who we think they are.