First, Lewis did not intend it at a puzzle, but as an unobtrusive or even subliminal part of the Narniad. He did not want it to be deciphered, but experienced. The discovery, then, might well ruin the effect.
But more importantly for this post, Ward points out Lewis's secretive nature, which has gone largely unobserved. Those who have read the biographies of Lewis have debated whether Lewis had a sexual relationship with Mrs. Moore early on. I won't weigh in on that. But the glaring fact, hiding in plain sight, is that he had this woman a generation older than him (plus her daughter) living with him until she died, and he offered only the most meager explanation of her presence. He made almost no reference to her in his writing or among his friends. Next, he hid his marriage to Joy Davidman even from his friends for over a year. Yes, there is "an explanation" why he did so, and we may take it to be true. But the explanation was mostly given only in his writing and correspondence, long after. If the explanation was so prosaic and unremarkable, why conceal it from his friends?
His autobiographical stories of early lying to his father about his life events, though they seem merely unfortunate and not serious deception in Surprised By Joy, take on a new light when we begin to see Lewis as a person who was almost unbearably candid in some ways, but yes, quite secretive in others. Two of the Inklings, in fact, referred to the book as Suppressed By Jack. This from close friends. There is even taking the name "Jack," a nickname he gave himself in childhood, as his preferred form of address throughout his life. Odd. He took numerous pen-names throughout his career.
It was not only negative secrecy. Lewis's charities were always hidden and often anonymous. I had long ago heard and since believed, that the Chronicles were dashed off in single or at most second drafts - an accomplishment of brilliance I have repeated with some amazement. It turns out to be completely untrue. Complexity, whether in art or personality, is not easily separable from privacy.
Candor can be a form of secretiveness, or an aid to it, for if one gives people a bit too much information, they withdraw from asking any further, or wondering what might lie behind. To go on about one's sciatica is to neatly prevent others from asking about your digestion.
Both Tolkien and Owen Barfield described Lewis as a thorough mystery to them. Michael Ward gives evidence for his theory that Lewis was painfully aware of this disconnect between various aspects of himself and made it his life's work to integrate them into a single person. The word "integrity," note, is derived from the same root, related to this idea of all aspects being part of a whole. Ward gives Jack Lewis credit for ultimately succeeding at this far better than a typical man, as evidenced by his writings and his actions in the last few years of his life. The last novel is entitled Til We Have Faces. The immediately posthumous literary work The Discarded Image. Ward does not suggest that Lewis took these titles as any coded message - they are entirely appropriate to the books themselves for other reasons - merely that these themes which had consumed his internal life found some completion in his later years, and the metaphors might quite unconsciously appeal to him.
It is only at this point that Ward notes
Anyone familiar with his poetry will know that it manifests an almost staggering degree of phonetic and metrical complexity, and the poems which look as if they are free verse are actually in the most complicated metres of all.And then, the major criticism (begun by Tolkien) - that the Narniad was an unfortunate hodge-podge of disparate elements, is counterbalanced by the number of readers over the years who have suspected that something was up with the series, and suggested it dealt with the Seven Deadly Sins, or the Seven Catholic Sacraments, or the Seven Virtues (three theological and four cardinal), or the Faerie Queen in miniature, and on into a dozen other possibilities.
The medieval planets, and the spirits thereof, suffuse Lewis's poetry from earliest years, and the Ransom Trilogy is founded on them. We ask, quite fairly: Would you expect this person to write a hodge-podge series of books, while writing nothing else, late in his career? And thus, before Planet Narnia has given the slightest evidence that The Lion, The Witch, and The Wardrobe is meant to surreptitiously convey a jovial (in the fullest, older sense) spirit, I was quite ready to believe that this, or something very like it, was possible.
But did it work? Given that Lewis attempted this, did he accomplish it? Those, I think, are questions with many answers.