The basic premise is that the books are grouped to create a display that has impact. Situated opposite the front door, they are the first things that you see upon entering our dear little house. If you're clever you might notice that the books behind the bobbin are arranged according to colour. This allows the bookcase to be an ever changing, colourful display of books and treasures. A bookcase should be interesting, it entices you to want to peruse the books in an idle moment (or even a really busy one when you'd much rather be curled up with a good book!).
I will continue to document the evolution of 'Project Bookcase' as it develops further.
Assorted bobbins available from Doug Up On Bourke.