It’s quite a simple idea to arrange books on shelves by colour, like this rainbow arrangement:
(We’ve tried something similar but in practice, you are rather limited by the books you have available. And most of ours have pesky writing on the spines in a variety of fonts. Which is great for when you are trying to locate something but does affect the aesthetic!)
Anyway, this beautiful arrangement was in the Sunday Times Style Magazine 13 July 2014:
As you can see, it doesn’t follow the spectrum strictly, but it looks beautiful and something that might – just – be achievable on a practical, domestic basis. Definitely an inspiration for when the nights draw in and the house needs a new look.