Belle da Costa Greene (1879–1950) and Junius S. Morgan II (Pierpont’s nephew and adviser on Library matters) met when both were working at the Princeton University Library—Junius as a librarian and she likely as a cataloguer. In 1905 Junius engaged Greene to help prepare Morgan’s books for transport to the new building, which was nearing completion. On Junius’s recommendation, Morgan soon hired Greene to manage his Library.
Greene was a de facto site manager while construction was in the final stages. She went on to run the Library for the rest of her working life, ultimately serving as the first director of what is now the Morgan Library & Museum and remaking a private treasury into a center for scholarly inquiry and public engagement.