1. On Tor, com, Mari Ness muses on the question, where should a first-time reader begin with C.S. Lewis's Chronicles of Narnia?
And comes up with the right answer: The Lion, the Witch and the Wardrobe, the one that was published first. In fact, just about everybody who's seriously considered the question gives that answer. Everybody, that is, except the publisher, who's given them official numbers with the later-published prequel, The Magician's Nephew, coming first, and Lewis's literary executor, who talked them into it.
Ness astutely points out that "The Magician's Nephew pulls away quite a bit of the magic." But its function as a later explanation of earlier events, that should come after the initial intriguing mystery, can be demonstrated objectively as well as subjectively. The Magician's Nephew begins by stating, "It is a very important story because it shows how all the comings and goings between our own world and the land of Narnia first began." This is addressed to a reader who already knows what Narnia is and why a story about it would be important. In the first paragraph that a reader ever encounters about Narnia it makes no sense whatever.
In chapter 7 of Lion, by contrast, when Mr. Beaver whispers that "Aslan is on the move," Lewis tells us that the children are all moved by this in a mysterious way, even though, he adds, "None of the children knew who Aslan was any more than you do." Look at that: if you don't know who Aslan is, then you are a reader who has never read about Narnia before, and who specifically hasn't read The Magician's Nephew.
Could it be any clearer? Lion comes first. If Lewis had wanted to change that, he'd have to rewrite the books.
Ness does record that "C.S. Lewis himself once told a young fan that chronological order was probably the best way to read the series." Not quite, and this had better be unpacked. The source is a letter, dated 21 April 1957, to an 11-year-old American boy named Laurence Krieg, and its supposedly definitive statement on an ordering is: "I think I agree with your order for reading the books more than with your mother's."
First, may we observe how hesitant and tentative this is? I think I agree ... more than with the other. In fact, the letter goes on to explain that the series was unplanned, and that at least through the third book Lewis never had any idea he was going to write any more than he had. "So," he concludes, "perhaps it does not matter very much in which order anyone reads them." This is about the opposite of a definite statement.
Second, perhaps Lewis is being polite to his juvenile correspondent? I was once told by another former boy of my acquaintance that Lewis had once written a letter to him saying the opposite; unfortunately the recipient didn't keep the letter.
Third and lastly, may we remember that Lewis is writing to a Narnian enthusiast who first heard the books read aloud at age 6 and has, by now, presumably read the whole series several times. Perhaps an experienced reader should re-read them in internal chronological order. We're concerned with the first encounter. That's not a topic on the table in Lewis's letter.
For a first-time reader, Lion first. Always.