“My editor thinks so. These single-subject historical books on everyday things are a trend in the publishing biz. Cod. Salt. Tomatoes. Mushrooms. You name it. The trick is to show how your given subject changed the world and saved mankind. You’ve got it made if you can mix in some sex.”

“Sexy artichokes?”

Stocker opened a file folder containing copies of old manuscripts. “Sixteenth-century Europe. Only men are allowed to eat artichokes, which are considered to enhance sexual power.” He opened another folder and slipped out a photograph of a pretty young blond woman wearing a bathing suit. “Marilyn Monroe. 1947. California’s first Artichoke Queen.”

Angela lifted the box off the cart and deposited it on the table. She blew a strand of long blond hair off her face. “Can’t wait to see Artichoke: The Movie.”

“I’ll get you a ticket to the Hollywood premiere.”

Angela smiled and told Stocker to let her know when he wanted to get rid of the files. Stocker opened the box and dug into the contents.

Writing books on commodities wouldn’t have been his first choice, but the pay wasn’t bad, the travel could be interesting, and the books gave him visibility. As long as he wrote, he didn’t have to teach to pay his bills. He rationalized that as a subject, artichokes were better than kumquats.

Stocker had come to the American Philosophical Society to look for the type of obscure anecdotes that could spice up an otherwise dry topic. The Georgian-style building that housed the society’s library around the corner from Independence Hall in Philadelphia was one of the nation’s major repositories of manuscripts on many scientific disciplines from the 1500s to the present.

The organization had been founded in 1745 by an amateur scientist named Benjamin Franklin. Franklin and his friends wanted to make the United States independent in the fields of manufacturing, transportation, and agriculture. The society’s early members included doctors, lawyers, clergy, and artisans, as well as presidents Jefferson and Washington.

Stocker was riffling through the carton when his fingers touched a hard surface. He pulled out an envelope that contained a box bound in maroon-and-gold animal skin. Inside the box was a thick packet of crackly paper tied with a black ribbon that had been sealed at some point. The wax seal had since been broken. He untied the ribbon and peeled off the blank cover sheet to reveal words written in a tight longhand that identified the contents as a treatise on the cultivation of artichokes.

The material was an unexciting recitation of growing seasons, fertilizer and harvest times, with a few recipes scattered among the pages. One sheet of parchment was marked with Xs and wavy lines and several words of script in an unknown language. On the bottom of the packet was a thick cardboard sheet perforated with dozens of small rectangular holes.