A comment on this question points to the following from OU:

Likewise, when words are stamped on the edge of a book (as is the case with most library books), these letters are separated when the book is opened, and this should not be done unless the book is urgently needed.

(The page has a reference to a note but I couldn't find the note.)

This made me wonder if you are erasing if the letters were not fully formed at the beginning of Shabbat, i.e. the book was already lying open. When you turn each page you're changing the state of the letters stamped on the sides, but they weren't whole to begin with so is there a problem of writing or erasing? If one really wants to read that library book or use a stamped reference book on Shabbat, does opening the book before Shabbat (in a way that it won't close on its own) let him do so?

  • Are you assuming he's not reading so many pages that the words will be re-formed on Shabas, or does your question not assume that?
    – msh210
    Commented Aug 21, 2011 at 21:23
  • 1
    @msh210, that's a good point; I'm not assuming either way. Commented Aug 21, 2011 at 21:33
  • Note that according to many acharonim it is entirely permissible to open and close such a book on Shabbos. See judaism.stackexchange.com/a/90542/13438
    – Alex
    Commented Mar 20, 2018 at 0:07

2 Answers 2


If you will read so many pages that the words will re-form, then we are back to the same question if one can open a book with writing on the side.

If not, then adding pages will not add anything to the shape of the letter. As a side point, R Ribiyat in his lamed tes melachos sefer points out that he doesn't understand the common leniency of breaking the writing through putting a sheet of paper in between the letters, because it does not break the letters from one who looks at a 90 degree angle straight down at the writing. From here we could see that letters have to look like letters for one to be able to "write" them.

  • Re "we are back to the same question": well, not necessarily. I don't know about kosev, but by kosher, for example, there's an idea of shel kayama, which some hold depends on the intent of the one tying (IINM. CYLOR). If something similar exists for kosev, then closing a book may be permitted even if opening it is forbidden, depending on the intent in each case of the one who closes/closed it. Or other variables may similarly come into play. I'm merely thinking aloud, here, though: perhaps none of this is truly relevant.
    – msh210
    Commented Aug 28, 2011 at 5:35
  • @msh210, a better way to address the "viewed end-on" problem would seen to be to use a single piece of paper stuck into two places (so you get a paper "spine" that covers some of the writing). You could then move it as needed. I'm not aware of anybody actually suggesting this, though. Commented Sep 15, 2011 at 2:14

Yes! It has been recommended to me (by a rav who is not a posek, when I posed a similar question) that I place a bookmark in the book before shabas and leave it in while reading, thus avoiding the problem in the question as well as the one in @tomsmith's informative answer.

  • Are your bookmark and @tom smith's piece of paper the same thing? I can't tell from these descriptions. And do you leave the bookmark where it was or do you move it as you read? (Could you share the identity of the rav?) Commented Aug 29, 2011 at 1:28

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