"The Magician's Nephew" was written years after all the other Chronicles but it was meant to be read first as a prequel.
It tells about the Creation of Narnia, and how Evil entered it.
There's a tree, a beautifully fragrant apple that is good for the pure of heart but bad for wicked ones. Because when you take something that doesn't belong to you yet, it usually leaves a bitter taste in your mouth.
There's various tests, trips between different worlds, friendship, generosity, and the idea that when one chooses to be loyal and yealding things will go well.
A great lesson not just for children but for adults too.
A juicy apple from my dad's tree.