Here's a game I like to play. What quote from the book would you put on the back of each Narnia book, or each book jacket, as an introduction to new readers? Here are my choices.

It was almost quite dark in there and she kept her arms stretched out in front of her so as not to bump her face into the back of the wardrobe. She took a step further in-and then two or three steps-always expecting to feel woodwork against the tips of her fingers. But she could not feel it. 
"This must be a simply enormous wardrobe!" thought Lucy, going still further in and pushing the soft folds of the coats aside to make room for her. Then she noticed there was something crunching under her feet. "I wonder is that more mothballs?" she thought, stooping down to feel it with her hand. But instead of feeling the hard, smooth wood of the floor of the wardrobe, she felt something soft and powdery and extremely cold. 

The Lion, the Witch and the Wardrobe 

"First of all, I'm a messenger of King Caspian's."

"Who's he?" asked four voices all at once.

"Caspian the Tenth, King of Narnia and long my he reign!" answered the Dwarf. "That is to say he ought to be king of Narnia and we hope he will be. At present, he is just king of us Old Narnians-" 

"What do you mean by Old Narnians, please?" asked Lucy. 

"Why, that's us," said the Dwarf. "We're a kind of rebellion, I suppose."

"I see," said Peter. "And Caspian is the chief Old Narnian."

"Well, in a manner of speaking," said the Dwarf, scratching his head. "But he's really a New Narnian himself, a Telmarine, if you follow me."

Prince Caspian

The things in the picture were moving. It didn't look at all like a cinema either; the colors were too real and clean and out-of-doors for that. Down went the prow of the ship into the wave and up went a great shock of spray. And then up went the wave behind her, and her stern and her deck became visible for the first time and then disappeared as the next wave came up to meet her and her bows disappeared again. At the same moment, an exercise book which had been lying beside Edmund on the bed flapped, rose and sailed through the air to the wall behind him, and Lucy felt all her hair whipping round her face as it does on a windy day. And this was a windy day, but the wind was blowing out of the picture toward them. And suddenly with the wind came the noises-the swishing of waves and the slapping of water against the ship's sides, and the creaking and the over-all high steady roar of air and water. But it was the smell, the wild, briny smell, which really convinced Lucy that she was not dreaming.

The Voyage of the Dawn Treader 

"I wonder what sort of a man that Tarkaan is," he said out loud. "It would be splendid if he was kind. Some of the slaves in a great lord's house have next to nothing to do. They wear lovely clothes and eat meat every day. Perhaps he'd take me to the wars and I'd save his life in a battle and he'd set me free and adopt me as his son and give me a chariot and a suit of armor. But then he might be a horrid cruel man. He might send me to work on the fields in chains. I wish I knew. How can I know? I bet this horse knows. If only he could tell me."

The Horse had lifted its head. Shasta stroked its smooth-as-satin nose and said, "I wish you could talk old fellow."

And then for a second he thought he was dreaming, for quite distinctly, though in a low voice, the Horse said, "But I can talk."

The Horse and his Boy

"Pole, I say, are you good at believing things? I mean things that everyone here would laugh at?"

"I've never had the chance," said Jill, "but I think I would be."

"Could you believe me if I said I'd been right out of the world-outside this world-last hols?"

"I wouldn't know what you meant."

"Well, don't let's bother about worlds then. Supposing I told you I'd been in a place where animals can talk and where there are-er-enchantments and dragons-and-well, all the sorts of things you have in fairy tales." Scrubb felt terribly awkward as he said this and he got red in the face.

"How did you get there?" said Jill. She also felt curiously shy. 

"The only way you can. By magic."

The Silver Chair

"Congratulate me, my dear boy," said Uncle Andrew, rubbing his hands. "The little girl's gone-vanished-right out of the world."

"What have you done to her?" 

"Sent her to-well-to another place."

The Magician's Nephew

"You look wonderful, wonderful," said the Ape. "Why, if anyone saw you now, they'd think you were Aslan, the Great Lion himself."

"That would be dreadful," said Puzzle.

"No, it wouldn't," said Shift. "Everyone would whatever you told them."

The Last Battle