I watched a BBC documentary yesterday about the work of Dr Michael Ward on The Chronicles of Narnia. His fascinating thesis is that the 7 Narnia books each correspond to one of the seven planets in the the Medieval worldview (inc. sun and moon). Really very interesting and I am likely to read his book now (Planet Narnia, OUP).
You can visit his website here.
You can watch the program here but only for a few more days.