I am using library a lot when I dont know what to read next. There are hundreads of books and if something interests me, I read it. However if some of those books really gets me into reading and I start to adore it, better if its book series, I start buying them. It is such satisfaction seeing my library grow and seeing the old titles that I wont forget, luckily my kids will read them. It is maybe just sentimentality, but I love to buy series of books. Some of them even read again, but most of them are just nice for look. And whenever I look at then, I remember the great stories and they make smile on my face :)