Some clues about the printing history can help identify the print run year. For example, the inclusion of the "Lectures" began in 1914. Additionally, the "Editor's Introduction" in volume 50 includes a second "Editor's Introduction" that is dated in 1917. Fabrikoid was first used as binding for The Harvard Classics in 1919. Lastly, the publishing company marketed a larger size of books with the Home Library edition. This set of The Harvard Classics and subsequent editions are 15 percent larger than previous editions. None of these clues allow for an exact printing year, but each can be used to establish that the printing could not have occurred before a certain year, and of course, the printing cannot have occurred before the most recent copyright date.