Errata lists in the early days of printed books, then, were themselves a sort of early comment section—the place where revisions were made and ideas were exchanged. They were "confessional spaces" and "emblems of a new culture of accuracy," but errata lists were also a way of seeing books as a collaboration between reader and writer, rather than just the one-way broadcasting of a set of ideas. Which means that print, in its infancy, didn't actually lead to "better, more accurate texts," but to "the dissemination of blunders," Smyth says. It is in this way that the dawn of book printing sounds a bit like where we find ourselves today on the Internet—a fluid and collaborative space for ideas that sometimes seems to be equal parts information-rich and error-riddled. The difference in early print, though, is that errors "were not hidden away." And while screengrabs capture some evaporated Internet writing for posterity, much of what's published today simply disappears or changes with all the imperceptibly of a distant keystroke.

It's ironic, then, that the motivation behind erasing errors online is tangled up in the expectation that Internet text mirrors what we know of print. At a moment when print text and Internet text are overlapping, the latter is still trying to look like the former. The same way early TV was radio-esque, and early radio took cues from print, the first books tried to mirror the manuscripts that came before them.

"Both print and the internet, as new technologies, worked to conceal their novelty," Smyth told me. "Early printed books often looked like handwritten manuscripts, just as Kindles today model themselves on printed books."

What we've lost, in many cases, online, isn't the integrity of print, but the traceability of its weaknesses. Centuries ago, "errata lists became, paradoxically, markers of well-made books." The made in "well-made" is a key word here. Mistakes can serve as reminders that books are made at all—the physicality of the process, the "connection between the book going wrong, momentarily, and a sense of the process of production being briefly revealed, or implied," as Smyth put it in a recent paper about print in Early Modern England. It's why readers relish newspaper typos—they represent the lifting of a veil, and hint at the human (and that human's fallibility) on the other end of the object.

But more than giving a window into the physical process—the actual making—of book creation, acknowledging an error is a way of updating a book after its printing, a means by which the text evolves and changes over time. This helps explain some of the efforts to save 19th century marginalia—because a book is not just a reflection of the person who wrote it; but also, sometimes, the impression of its readers. Some readers, of course, leave more indelible marks than others.