If I borrow something may I do something which I believe improves that thing, without the owners consent? For example if I borrow a library book and find an error in one of the facts printed there can I write a correction in the margin?

  • 2
    One man's improvement is another man's damage. I would be surprised if "I believe it's an improvement" is strong enough to permit. Jun 12, 2013 at 21:12
  • Would the question be any different for "if I see an error in a book at a book store would I be allowed to write a correction in the margin?"?
    – WAF
    Jun 12, 2013 at 21:21
  • How about adding a diamond to a ring?
    – sam
    Jun 12, 2013 at 21:58
  • @WAF might be harder to sell a book that was written in, even if the writing improves the book Jun 13, 2013 at 1:14
  • @not-vram Might it not be similarly harder to lend out the book in the case of a library?
    – WAF
    Jun 13, 2013 at 1:16

1 Answer 1


The Chofetz Chaim in Ahavat Chessed part 2 chapter 22 writes about a borrower

He must beware not to break the terms stipulated by the lender. If he does, he is termed a gazlan (robber). He may not use the borrowed article for any purpose not stipulated, nor may he retain beyond the allotted time. [...] Frequently, too, the article is broken through the borrower's neglect. Even if he pays for it, this is still an injustice. The lender did not, in the first place, give him the article for such a purpose.

As such, one should ask the lender whether such an improvement is indeed beneficial to him. Absent such approval, I don't think one can make the hypothesis the improvement is always wanted (e.g., some people might be particular about not writing in their books).

A practical option is to write the correction on a note which you add to the book, and once you return it to ask whether they would like you to leave the note or correct the book directly.

Of course, consult your rabbi before implementing anything you learn here.

  • 1
    Hi, nice answer! I want to mention that there are some cases where an improvement could be made to another's property without their consent and still be entitled to compensation, although at a lower rate(where warranted and beneficial; like a repair). Although it seems to apply only to land and not metaltelin. See Shulchan Aruch Choshen Mishpat 375 for more. Generally speaking though, the halacha is that it's forbidden to use an item other than for it's purpose(and in normal fashion) without consent of the owner. In the case above, the library is the owner of the book and not the lender. Feb 5, 2019 at 11:05

You must log in to answer this question.