Do I need less books or just more shelves?

I worked from home today and as I was making a cup of tea I was looking at my lovely bookshelves my husband made them for me when my books started taking over the house. They now seem to have outgrown the shelves as well ( I have more of the same on the adjacent wall). So do I need less books or more shelves? Looks like my husband has some work to do ;-)