Here is today's Latin LOLCat. Of course this saying applies to many more things than just books: it is the USING of things, not just the having of them, which matters. If you are interested in Latin proverbs and fables, check out the Bestiaria Latinablog.
Libros paucos legere utilius, quam multos habere.
It is more useful to read a few books than to have a great many of them.