Have you ever wondered what specific kind of apple tempted Eve? For one New Yorker in 1956, it was a question that plagued them enough to call up the library to find out. In a box of old reference questions discovered by the New York Public Library, the breadth—and bizarreness—of human query was revealed in a number of handwritten notes documented by staff.

Some of the calls are particular to their era: One caller in 1947 inquired after the physical characteristics of Adolf Hitler. “I think I’ve found him,” they said. “He walks heavier on one foot and everything.” Others are timeless concerns, like the “somewhat uncertain” woman in 1967 who wanted to discreetly track down the identity of a fellow she knew to be worth $27 million.

In a pre-digital age, knowledge was f...