With the announcement that Harper Lee -- whose best-selling, and only, book debuted more than 50 years ago -- will finally publish her second novel, a handful of questions were naturally raised. Chief among them: Why hasn't she produced more works since 1960, when her classic “To Kill a Mockingbird” was published? The famously private author has never provided a clear answer, leaving many to resort to speculation and conjecture. But interviews over the years with those close to her, as well as her track record of avoiding publicity, offer clues.

While writing a biography of Lee, “The Mockingbird Next Door,” Marja Mills asked the same question of Lee, her sister and a family friend. Lee’s first novel had raised “impossible expectations,” Mills was told. The success of the biography, which was published last July, also generated publicity that Lee hated and seemed to shy away from. As her sister, Alice Finch Lee, once explained, “When you have hit the pinnacle, how would you feel about writing more? Would you feel like you’re competing with yourself?”

Still, the fact that Lee published only the beloved “To Kill a Mockingbird” did not mean she wasn’t still writing. In the late 1950s and '60s, she collaborated extensively with Truman Capote, her childhood friend, on an article he wrote for the New Yorker, interviewing and doing research for the story that was to grow into his seminal work “In Cold Blood,” on which Lee also helped.

In the mid-1960s, Lee was rumored to have written a second novel that was never published. She also worked on “The Reverend,” a nonfiction book about a serial killer in Alabama. But that, too, never came out. Later, she retreated from public life, dividing her time between New York City and her hometown of Monroeville, Alabama.

Perhaps it was this fear of failure -- of not meeting or exceeding the standard that “To Kill a Mockingbird” had set -- that led Lee to refrain from publishing those additional works and others. Perhaps even greater was the fear of attention she so painstakingly avoided. The arrival of her second book this summer may finally provide some answers.