“The codex comes from a family of documents from the same town,” Seiferle-Valencia said. “This is the largest, the most heavily illustrated and one of the most complex. It’s the jewel of the group.”

Espinosa, an art enthusiast who owns a private art museum, first heard about the codex almost two decades ago, when its previous owners contacted her and invited her to see it.

“It is very powerful,” she said. “If you asked a child to read it, maybe they could understand it better than we do...I saw it, and I kept dreaming about it.”

But the owners refused to sell Espinosa the treasure. After viewing the codex three times—folded and tucked away in its dark safety deposit box—and repeated attempts to acquire it, the owners finally agreed to sell it to her.

Although the codex project will be privately funded—and the work itself cannot leave Mexico for legal reasons—Espinosa, a trustee of the David Rockefeller Center, approached Coatsworth about getting the Center involved with the project after a board meeting.

“Mrs. Espinosa was the primary impetus for this project,” Seiferle-Valencia said. “She wants to know about the codex, to get scholars involved, and to contribute to the public.”

Espinosa said she hopes the codex will help people to “better understand all Mexican history.”

—Staff writer Ella A. Hoffman can be reached at ehoffman@fas.harvard.edu.