Since this past summer, I've been reading the books and essays offering their authors' lists of the "great books"--generally of Western civilization, but several include literature spanning the entire globe. I want to compile, and quantify in some fashion, these varied canons, or rather those which cover all of literary history. Plenty of shorter lists, whether they are Western-centric or not, confine themselves to recent history, especially the Twentieth Century. Only about twenty authors, newspapers, organizations, et al. (that I have found so far) have created all-encompassing lists. Several of them do not designate the literary works included as the greatest or best--they are vaguer in their recommendation; they are included nonetheless.
The difficulty of quantifying these lists comes from the lack of uniformity among the type of literary works included, even within a particular list. For the most part, distinct works are listed: poems, novels, histories, short stories, novellas, etc. Varied collections of works, though, are often listed: the complete works of an author, a series of novels, or--most confusing--undefined selected works. Therefore, an entry--let's call it--in a list of, say, 100 works, could itself be 20 works; and thus a list of 100 works becomes 119.
The other problem that has emerged comes from the multiple titles used for older works, especially those of unknown date or authorship. The librarian in me wants to distinguish between uniform titles and varied formal and informal titles. The title of certain works has been a matter of dispute, most notably perhaps The Arabian Nights vs. The Thousand and One Nights.