Because according to Mr. Rodriguez’s statement in the affidavit, the book was compiled by employees of Mr. Epstein, not by Mr. Epstein himself. Those contacted for this article acknowledged having met Ghislaine Maxwell, Mr. Epstein’s former girlfriend and “lady of the house,” and posited perhaps that was how their names ended up in the book. (It is unclear from the affidavit whether Ms. Maxwell is one of the “employees.” Ms. Buck said that she had met Ms. Maxwell at a boutique opening but that “she never phoned me.”)

The Little Black Books of Men

Mr. Epstein’s book has become a symbol of the exclusive world of the very famous and very rich, and the secret life the financier lived.

That makes it the latest in a line of “little black books” that have played key roles in crime stories as far back as the mid-18th century, when Samuel Derrick conspired with Jack Harris, the “Pimp General of all England,” to create an annual guide to London’s prostitutes and their specialties. It ran hundreds of names long and was known as “Harris’s List of Covent -Garden Ladies.”

Ever since, the term “little black book” has come to represent something of a secret directory both in true crime tales and in the arts; a list passed along among insiders and conspirators; a source of illicit knowledge and a record of it that could be weaponized. The little black book has transcended mere notebook status to become a cultural trope, symbol and narrative device. (Also, on occasion, a gift item.)

The designation “black book” at one point referred to official records, most often the ledger of the British exchequer. It may have been borrowed for more prurient record keeping.

Hallie Rubenhold, the historian and author of the 2005 book “The Covent Garden Ladies,” said she thought that the proverbial book was a combination of two items popular with 18th-century gentlemen: the annual release of Harris’s list and the black leather-bound diaries that were available for purchase every year around Christmas.