A pair of books, 60 years overdue, were returned in a mailed package to the Boston Public Library’s Copley Square branch Tuesday.

Library officials said they were so grateful to have the books back that they would not charge the person the late fee, which at 10 cents per day would equal $4,391.80, according to the Herald.

The returned books were the “Autobiography by John Stuart Mill” and “The Writings of Henry David Thoreau.”