Juliet replies to Dawsey and explains that she's thrilled his letter reached her, as she no longer lives at the address written in the cover of the Charles Lamb book. She wonders how the book ended up in Guernsey. Juliet says that she loves going to bookshops so upon receipt of Dawsey's letter, she went to her favorite bookshop and asked the proprietor to send Dawsey a copy of More Essays of Elia and put him on the hunt for a biography.
Juliet's desire to help Dawsey shows just how much she values literature and helping others connect with it as well. By writing him back, she makes sure that their correspondence can continue and with this, that they can continue to connect with each other over their shared love of literature.
Juliet says that she's enclosed a copy of Charles Lamb's Selected Letters as a gift, which she believes is a better way to learn about Lamb than through a biography. She includes her favorite passage and explains that she only began reading Lamb's work after learning that Lamb, while visiting a friend in prison, helped his friend paint a mural in his cell, offered money to the friend's family, and taught his friend's daughter to say the Lord's Prayer backward. Juliet says that this is her favorite part about reading: tidbits like these lead a person into book after book with no end in sight. She says she's included a postcard of Charles Lamb's portrait.
By sending Dawsey Charles Lamb's letters, Juliet holds up the power of personal correspondence as the best way to get to know someone. This feeds into the structure of the novel as a whole, as this is exactly how the reader learns about the various characters. Juliet's comments about how one book leads to another also indicates that books don't just connect people to each other; they connect dedicated readers to even more books and new authors as well.
In closing, Juliet asks Dawsey if he'd answer three questions for her about the secret pig roast, how the Society began, and what a potato peel pie is and what it's doing in the Society's name. She gives Dawsey her current address and laments that her old flat was bombed in 1945.
Juliet's interest is piqued mostly because the Society represents, for her, a group of people who might love books just as much as she does—in other words, she sees them as potential friends thanks to their shared love of literature.