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.
A child, more than all other gifts
That earth can offer to declining man,
Brings hope with it, and forward-looking thoughts
—Wordsworth
William Wordsworth, a major player in the British Romantic movement, which obsessed over the natural delightfulness of children, was famously obsessed with kids. All that business about children being our future? That's straight from the Romantics.
By opening with an epigraph from Wordsworth—specifically from "Michael: A Pastoral Poem"—Eliot announces that this book is going to be (1) about the country, and (2) about children and parents. The funny thing is, "Michael" is not a cheerful tale. Michael and his son Luke live in a thrifty pastoral utopia, earning the respect of all their village neighbors and basically living out the dream of the English countryside. Until…
Yeah, it doesn't last. Turns out, Michael has co-signed a loan for his nephew, and his nephew has defaulted. Luke has to go off to the city to make money to pay back the loan, and, of course, he gets into bad company and ends up fleeing England. Michael dies of a broken heart, his wife follows, the cottage is sold, and, with understatement, Wordsworth announces that "great changes have been wrought / In all the neighbourhood" (478-479).
In other words, "Michael" tells the exact opposite story that Silas Marner does. The child ruins the family rather than saves it; the young man goes to the city and is corrupted rather than leaves the city and is saved. Keep in mind that "Michael" was published in 1800, sixty-one years before Silas Marner. Wordsworth was writing about the changes of urbanization and industrialization as they were happening; Eliot is reflecting on them from decades later. So, is Eliot being ironic? Does she not believe the story she's telling? Did she specifically set out to complicate the story of "Michael," or is this epigraph a clue that Silas Marner is nothing more than an idealistic fairytale?