I am horrified at the number of gardeners - people I always thought must be among the most upright citizens in the world - who haven't make the connection between keeping library books and stealing...no wonder we have a problem in North America with cheating in schools and universities - our young people are learning from the example of their elders. One person commented that she had a book from September till after Christmas and wasn't bothered by it because she thought no-one else would be looking for it. That's not her decision to make. I once wanted to borrow, long-term, a weaving pattern book that it appeared no-one else was borrowing but I made a deal with my librarian that if she phoned me to say some-one else was asking for it, I'd have it back within 24 hours...and I did and then went and bought a copy myself - it was very expensive but by that time I knew I needed to have it always by me.
Not returning library books is stealing - no ifs, ands or buts. Stealing! Not just stealing from the library although if we all did it, the libraries would soon be empty; but stealing from all the other people who use that library. They have as much right to the books as anyone else and you deprive them, by keeping a book, of their ability to exercise that right.
Would you attempt to keep a rental car for weeks after it was due back? No, of course not and not least because the car rental company would soon have the law after you...all of those people who have tried to make it seem funny that they steal books that belong to everyone who lives in their town, need to take a long, hard look at their attitude to honesty.