Eco: I'm afraid that, by now, it might actually be 50,000 books. When my secretary wanted to catalogue them, I asked her not to. My interests change constantly, and so does my library. By the way, if you constantly change your interests, your library will constantly be saying something different about you. Besides, even without a catalogue, I'm forced to remember my books. I have a hallway for literature that's 70 meters long. I walk through it several times a day, and I feel good when I do. Culture isn't knowing when Napoleon died. Culture means knowing how I can find out in two minutes. Of course, nowadays I can find this kind of information on the Internet in no time. But, as I said, you never know with the Internet.
[ thx @amadad & @slavin ]