"The handwriting on the back was different from the presentation inscription, which was very curious," Whitesell said.

When he opened the back cover he found pages of manuscript poetry in the same handwriting--it appeared that Dario had written new poems on the blank pages of the slim volume.

"I was very intrigued and a bit skeptical," Whitesell said. "It didn't seem to be that I could just open a book and find manuscript poetry from Ruben Dario."

And so Whitesell replaced the book on the shelf and went home, "doing something I immediately regretted."

After the proverbial "sleepless night," Whitesell returned in the morning and compared the handwriting in the book to known samples of Dario's writing and found them to be identical.

"I looked at Dario's collected poems and found that two had been previously published," he says. "Here were the earliest known drafts with textual differences, but the final two I couldn't find anywhere. They were presumably unknown and unpublished."

To confirm his hunch that the University's holdings contained book's from Dario's personal library, Whitesell hunted through Harvard College Library's acquisition records and found correspondence between a book seller in Madrid and the University in 1916, the year of Dario's death.