Originally Posted by jusmee
If I own something, I should be entitled to let a friend borrow it for a while. I can't believe anyone can reasonably argue against this.
But you're not "letting a friend borrow it"; you're giving your friend a copy of the book. Previously only you had a copy; now, both you AND your friend have a copy. Two books exist where previously there was only one. It's like photocopying a paper book and giving your friend the photocopy. That's why this is not permitted.