It's a well-known literary fact that William Shakespeare had an enormous influence on "Paradise Lost" poet John Milton, and new evidence suggests that super fan Milton—who even wrote a poem called "On Shakespeare"—might have owned his idol's first folio.

The folio, which contains 36 of Shakespeare’s plays, was published in 1623—seven years after the Bard’s death. An estimated 750 first folios were printed, with only 233 of them known to have survived, including one with annotations written throughout it. As it turns out, those scribbles might be Milton's.

According to The Guardian, Cambridge University fellow Jason Scott-Warren believes that Milton wrote those important annotations. Scott-Warren read an article about an anonymous annotator written by Pennsylvania State University English professor Claire Bourne. The Folio copy in question has been stored in the Free Library of Philadelphia since 1944, and Bourne was able to date the annotator back to the mid-1600s. (Milton died in 1674.) It was Scott-Warren who noticed that the handwritten notes looked similar to Milton’s handwriting.

"It shows you the firsthand encounter between two great writers, which you don’t often get to see, especially in this period,” Scott-Warren told The Guardian. “A lot of that kind of evidence is lost, so that’s really exciting.”

If the writing does indeed belong to Milton, it’s not the first time the poet has left notes on another writer's work; he supposedly marked up his copy of Giovanni Boccaccio’s Life of Dante as well. Scott-Warren and Bourne plan to pair up to find out if Milton left annotations on any other notable works.

"It was, until a few days ago, simply too much to hope that Milton’s own copy of Shakespeare might have survived—and yet the evidence here so far is persuasive,” Dr. Will Poole, a fellow and tutor at Oxford's New College said. "This may be one of the most important literary discoveries of modern times."