I'm not one for collecting stuff for the sake of collecting stuff, but I do have a fair number of books. Some of them are for reference, and a lot of them hang

I'm not one for collecting stuff for the sake of collecting stuff, but I do have a fair number of books. Some of them are for reference, and a lot of them hang around because it's easier to put the book on a shelf once it's read than take them down to the second-hand store. You analogy isn't the best, because one guitar is a reasonable substitute for another guitar, whereas a Mr Men book doesn't substitute for, say, "Modern Compiler Implementation in ML".