If my library burned down?

I like to read a lot of non-fiction, mainly scientific or technical books. Now I am in the process of reading two books simultaneously, one of which is Finding Moonshine by Marcus du Sautoy. The book is about symmetrical objects in mathematics, and perhaps this blog is not the right medium to discuss the book in detail. What I am more interested in today is a remark the author makes in a certain context in the book. He quotes someone saying which book that person would pick up if his library burnt down. And that got me thinking. Which book would I pick up, if my modest library at home burned down for some reason?