I once heard a speaker at a writing conference insist that theme was the most essential element in any novel. Chagrined, I realized I couldn’t identify the theme in my then unfinished first novel. As she spoke, I reached for the sweater I’d hung over my chair. I felt exposed for the lack of a theme.

Looking back, I realize that establishing a theme early on was that writer’s entry point to her work. I, on the other hand, had started with a vaguely formed character, a wisp of a plot, and a glimpse of an ending.

I had a hunch that there was a theme buried in the story, but the execution was, as author George Saunders suggests, “more of a cartoon or line drawing than a fully executed oil painting or photograph. . . alluding to the real deal, but doing so while being somewhat sketch-like.”

Saunders says this approach makes a good short story, but does a longer work of fiction require a more extensive and overt execution of theme?

I recently reread Jonathan Lee’s marvelous Gilded Age novel The Great Mistake. When I initially finished it, I wondered just what the great mistake was. I assumed it was the murder of the protagonist that happens in the first chapter.

Andrew Haswell Green, identified as the Father of New York City, was instrumental in the establishment of Central Park, the Metropolitan Museum of Art, the Natural History Museum and the Bronx Zoo, amongst other NYC institutions. But despite his good works, as we find out in the opening pages, Green was shot dead on his doorstep at age 83.

On a second reading (in preparation to lead a book club discussion), I found several other significant “mistakes”—the lack of affection and approval from Green’s father; the consolidation of NYC’s boroughs, referred to at the time as the Great Mistake of 1898; and the almost complete disappearance of Green from modern public awareness. I also wondered if Green thought of himself—a gay man in a less accepting time—as a great mistake.

But alongside these larger mistakes, Lee introduces smaller ones in nearly every scene. The book is filled with misunderstandings, errors, wrongdoings and missteps that illustrate how our mistakes make us who we are, which is what I took as the theme of this novel.

I hadn’t read Lee’s novel when I went in search of my first novel’s theme. But after the conference presentation, I paid attention to themes in other novels I was reading. And by identifying others’ themes, I recognized my own. I was writing about finding home through telling a fictionalized version of my Swiss great-great-grandmother’s immigrant story. During my next round of revisions, I emphasized that theme in subtle revisions of the plot, dialogue and my protagonist’s interior thoughts.

I wanted these smaller theme treatments to work in tandem with the more obvious examples. They became the warm base layer that drove my story—barely visible, but as essential as a cozy outer layer to envelope the reader in my theme.