Web 3.0 anyone?
After a little research on the subject ((It sounds very professional, doesn’t it? What about
s/research/googling/?)) I discovered that at some point books were visible on the shelves, as one can see in this other photo by canonsnapper.
Personally, I think the empty shelves are much more effective.
For people interested in the argument, here you find the relevant Wikipedia article. Quite interesting, especially if seen in the light of the recent try to censor the Internet. Learn from history.