As an alternative theory, (and because Latin scholars do this sort of thing) someone tracked down a 1914 Latin edition of De Finibus which challenges McClintock’s 15th century claims and suggests that the dawn of lorem ipsum was as recent as the 20th century.

The 1914 Loeb Classical Library Edition ran out of room on page 34 for the Latin phrase “dolorem ipsum” (sorrow in itself). Thus, the truncated phrase leaves one page dangling with “do-”, while another begins with the now ubiquitous “lorem ipsum”.

“What I find remarkable is that this text has been the industry’s standard dummy text ever since some printer in the 1500s took a galley of type and scrambled it to make a type specimen book; it has survived not only four centuries of letter-by-letter resetting but even the leap into electronic typesetting, essentially unchanged except for an occasional ‘ing’ or ‘y’ thrown in.»

Whether a medieval typesetter chose to garble a well-known (but non-Biblical—that would have been sacrilegious) text, or whether a quirk in the 1914 Loeb Edition inspired a graphic designer, it’s admittedly an odd way for Cicero to sail into the 21st century.