Oh, so that's what it means

I was helping a patron place holds for knitting books. While running the catalog through its paces, she mentioned that one of our knitting books that she had taken out recently had had pages cut out of it. We talked briefly about the barbarity of cutting up library books. She said that she thought that, to her, cutting up a library book was like vivisection. Then she leaned in and, all sotto voce, told me that vivisection meant "when they cut up animals." By the way, sotto voce means when you talk in a low, soft voice that unlikely to be overheard by others. And condescending means when you talk down to somebody.