LONDON - It's 150 years since a hookah-smoking caterpillar sitting on a mushroom asked a curious young girl called Alice "Who are you?" and readers have been wondering the same thing ever since.
Lewis Carroll's Alice's Adventures in Wonderland, with characters including the Hatter, the White Rabbit and the "off with his head" Queen of Hearts, has delighted generations of children since its publication in 1865.
Carroll first told the story on July 4, 1862 as he and a friend rowed 10-year-old Alice Liddell and her two sisters along the River Thames in Oxford.
The Hatter's mad tea party, the tears of the Mock Turtle and a croquet game in which flamingos are used as mallets make up a topsy-turvy world of delightful nonsense.
But Alice and Through the Looking-Glass, published six years later, continue to captivate adults with their brilliant and subversive portrayal of how the grown-up world might appear to a seven-year old.
"There are really two stories," said Oxford University academic Robert Douglas-Fairhurst, whose new book The Story of Alice reveals the history and impact of the stories and the relationships between their author and the real-life Alice for whom they were written.
One is a story to help children grow up "because it is about how confusing and surprising and disturbing the adult world is, but described in a comic and playful way".
"But it is also a book for adults, who want to recapture that sense of wonder that they might have lost." Take Alice's answer to the caterpillar.
"I - I hardly know, Sir, just at present - at least I know who I was when I got up this morning, but I think I must have been changed several times since then."
A perfectly understandable response after Alice's body has been shrunk and stretched but also one that resonates in an age when identity is fluid and changing.
Douglas-Fairhurst, university professor and tutor of English at Magdalen College, Oxford, says the books' author also raises questions of shifting identity.
Lewis Carroll was the pseudonym of The Reverend Charles Dodgson - a stammering, "rather stuffy" mathematics tutor at Christ Church, Oxford - for whom Wonderland was a break from his rules-based world.
"Nonsense isn't the opposite of sense, it's a kind of holiday from sense... they are the stories of Carroll's real-life self playing around with dream versions of what he had to spend his working hours doing," Douglas-Fairhurst said.
Throughout his life, Dodgson sought the friendship of young girls. He photographed many of his "child-friends", some naked, raising uncomfortable questions while he was alive and today, when child abuse has rocked many institutions.
Douglas-Fairhurst says there is no evidence that Carroll's feelings were anything other than paternal or protective.
"Was he secretly harboring forbidden desires for them? If he was, it was such a deep secret, even he wasn't in on it."
But today's focus on the child is arguably one more reason to read the books.
"I think today we are so nervous about children and childhood and that we want something we can use to understand them and Alice is a kind of inkblot or empty vessel we can fill with meaning."
The anniversary is being marked with events nationwide and, as has happened since the books first appeared, with new works based on Alice's adventures.
Among them, Les Petits Theatre Company is putting on two "immersive" productions - one for adults and one for children - in The Vaults under London's Waterloo Station.
At the Manchester International Festival, a new musical, wonder.land, with music by Damon Albarn of Blur and Gorillaz, tells the story of bullied 12-year-old Aly who escapes to a virtual online world.
"That's an example of how protean and slippery the stories are and that's why we like them," Douglas-Fairhurst said.