For no reason - just because I was listening to it on the radio.
Design wouldn't make much sense if you didn't know the book, but I think that's fair enough for a classic.
(I have now discovered why my pictures were coming out grey on my blog. Apparently it is auto'correcting' them. To stop it doing this, you have to change a setting in Google+. If you aren't on Google+ you have to join it - for the sole purpose of making your pictures appear as they should. Logical.)