Question: If one is reading a book on Shabbat and would like to mark a certain page by making a slight scratch with one’s nail or by slightly folding the corner of the page, would this be permissible on Shabbat?
The Forbidden Work of Writing
Answer: One of the forbidden forms of work on Shabbat is writing. Even if one merely writes two letters on Shabbat, one is liable for Shabbat desecration (even writing one letter is prohibited, but it is not as grave as writing two letters).
Making a Mark by Scratching Wooden Boards
The Mishnah in Masechet Shabbat (103a) states that the Tannaim disagree whether or not scratching a mark on wooden boards and the like will make one liable for the forbidden work of “marking” or does the Torah only prohibit actual writing. According to Rabbi Yoseh, if one makes a scratch onto a wooden board on Shabbat, one is liable for performing a forbidden work on Shabbat. Halachically speaking, the Tur (Chapter 340) writes that the Halacha does not follow Rabbi Yoseh. Similarly, Rabbeinu Ovadia of Bartenura and the Mishnah Berura (Be’ur Halacha ibid.) rule likewise. Indeed, Maran Ha’Shulchan Aruch and most Rishonim rule likewise.
Nevertheless, it is still forbidden to scratch a mark onto wooden boards on Shabbat as a result of a rabbinic decree. We shall now discuss whether scratching a light mark onto the page of a book with one’s nail constitutes at very least a rabbinic prohibition similar to scratching a mark onto a wooden board on Shabbat or is scratching on paper not considered a forbidden form of marking on Shabbat at all.
Scratching Paper or Parchment on Shabbat
Indeed, the Tur (Chapter 340) writes that one may scratch a mark onto paper on Shabbat. Maran Ha’Shulchan Aruch (ibid. Section 5) rules likewise. Their rationale is that any scratch which does not last for a prolonged amount of time is not prohibited at all on Shabbat. This is because our Sages only prohibited scratching on Shabbat when the mark will last for a long time, such a scratching wooden boards; however, a scratch made in a book only lasts for a short while and is not considered a forbidden form of marking on Shabbat. (We should point out though that making a scratch skin on Shabbat is forbidden.)
Some Acharonim, including the Turei Zahav, write that there is only room for leniency when the scratching is being done on parchment, for only then does the mark only last for a short while. However, one may not act leniently by scratching a mark onto a book. Nevertheless, the words of Maran Ha’Shulchan Aruch imply that there is no distinction between them, for in the days of Maran there were books being printed on paper and he nonetheless rules leniently in this regard.
Thus, one may scratch a mark, such as a line and the like, on the side of a page, for this kind of marking does not last for a prolonged amount of time, as we have discussed.