"Dear Luke,'' the letter began. ''It was a very kind and interesting letter you sent me and I thank you very much for writing it.''
My heart leapt. Forty years later, I do not remember the casual confidence with which I had sent my father on his address-finding expedition; but I do remember the intake of breath, the sudden sense of my world expanding, when I opened that envelope.
For the Tintin books were my emotional universe. To read them felt quite simply like being loved: in advance, and by an entire world of possibility, my future. Even today, the power of reading one of them remains visceral: each book acts as a form of transportation, not just to the emotional landscape of this first literary love affair but to very specific memories.
Mon dieu
King Ottokar's Sceptre.
One summer morning, the family began the trek up the Pacific Highway from home in Sydney to Surfers Paradise, where each year we spent our Christmas holidays. The usual 12-hour journey was interrupted when my little brother, Felix, who'd had an ongoing illness since birth, became sick and wound up having to spend the night in Grafton Base Hospital.
We booked into an old-fashioned pub by the Clarence River. The situation with Felix mustn't have been great because there was about an hour at dusk when our parents left me and my older brother, Ben, on our own in the hotel room. I remember feeling: ''OK. We're alone in an alien place and our parents aren't here. When they come back, they'll feed us.'' I curled up on my lumpy bed with Prisoners of the Sun and dived, transported, into its noir-ish, scene-setting opening panel: ''At police headquarters in Callao, Peru.''
Four decades later, I remember everything about that hotel room: the stripe of the bed cover, the great cedar cupboard, the gauze curtains, the wide verandah, the alkaline breeze from the river. And with it all I remember so vividly the unassailable cosiness, the sense of being protected, being in such an utterly foreign room and yet being, with that book in my hands, fundamentally safe. Certain books in my life have seemed psychically talismanic but only Tintin books ever felt physically so.
Letter to Herge
One of Davies' letters to Hergé.
From time to time it has struck me that as a writer I've somehow managed to live my life as I had long ago dreamt of doing, based on the Tintin paradigm: on my toes, travelling, senses attenuated, everything just adventure and exploration, curiosity and problem solving.
There's a frame in one of the books where Tintin is sitting in his cosy apartment having a boiled egg and toast for breakfast, reading the newspaper. In European cities, when I've sometimes rented an apartment to work on a novel or script, I have found myself thinking, in the middle of such a breakfast, and with a conscious, overt memory of that scene: ''Holy shit - I think I've pulled this off.''
At such a moment, one is infused with gratitude: that life, for all the unfathomable strangeness of its twists and turns, can now and again integrate, without static, the joys and dreams of the deep past with the radiant present.
We wrote several letters back and forth during the next few years. There was a remarkable consistency to his tone and style across the letters. ''I was especially delighted by your father's big idea of 'The Butterfly Farm','' he wrote. ''Respect for and interest in life are always a comforting show.''
(My father and his best friend, the novelist Kenneth Cook, had started a before-its-time ecotourist attraction on the banks of the Hawkesbury River at Wilberforce and the family moved there for a year and a half.)
I must have bombarded him with questions. ''I am married but have no children,'' he answered in one letter, ''except, of course, Tintin, Captain Haddock, Professor Calculus and all the others, and that's a family!''
There were elaborate Christmas cards, too. One, a frosted-gold scene of Tintin and the others going to church in the snow, opened up into a spiral that hung from the ceiling. Others showed various characters, disguised on an Egyptian tomb mural, or as figures on a sheet of stamps, or a crowd of protesters saying ''Non!'' to pollution.

One is even a full-page rough in progress from Tintin and the Picaros, Hergé´'s final completed book, complete with a trompe l'oeil ''best wishes'' card attached with a fake rusty paper clip.

Then it seems - to my great regret now - that with adolescence coming on, I simply stopped writing. And so did he. But every year for seven years the Christmas cards kept coming: extravagant, beautiful, playful.
And what of my side of the correspondence? Surely copies of my original letters to Hergé´ would not still exist? I wrote, without an enormous amount of hope, to the Hergé´ Foundation. The archivist, Bernard Tordeur, replied. He told me there were 50,000 letters in storage in a ''safe place somewhere out of Brussels'' and that while they weren't digitised, he would at some point try to see whether he could find mine.
My heart leapt all over again. I experienced even my sense of growing impatience as an intense sensation of good fortune. I was to get to see the way I thought, the way I wrote, 40 years ago. Primary sources! Eventually, Tordeur unearthed three artefacts only. There was nothing from those first couple of years and, unfortunately, no trace of the first letter I ever wrote Hergé´ at nine, which I craved as a kind of Holy Grail. But it was a priceless, personal goldmine nonetheless.
There's a letter from 1973 in which I appear to be doing exactly what I told my father I'd do: chit-chat. ''For our holiday we went down to Sydney and went to various tourist attractions, picture theatres, ferry-rides etc,'' I wrote. ''Mum and I went into a bookshop to buy a Tintin book for me, which is Red Rackham's Treasure. That now brings my collection to six of your books.''
There's one other letter, from a year and a half later; I was a few months short of my 13th birthday by now. ''Dear Mr Hergé´, I hope you are well. I'm sorry I haven't written to you for so long. I wrote one letter to you recently, but it must have got lost in the mail, as I never heard back from you.''
To the modern ear, in this era of chronic, overwhelming, yet-to-be-dealt-with email inboxes, there sounds a hint of the passive-aggressive in this. But it speaks to me of my innocence: I simply assumed only one possible explanation - lost in the mail - for any downturn in our correspondence.
''In 2nd form,'' I wrote, ''I have chosen for my two elective subjects French and Latin. Maybe I'll soon be writing to you in French." (Historical note: I never wrote to him in either language.)
Another of Tordeur's unearthed treasures is a school photo of me in my St Dominic's College, Penrith, uniform - a school I only attended for a year and a term, and a photo of which I have no memory. Hergé´ had sent me a photo of himself, signed in gold ink, for my 11th birthday. I suppose this was the reciprocal act. ''Dear Mr Hergé´,'' I inscribed on the back of the photo, ''With great affection, from Luke Davies (aged 11) (Australia).''
''You were relaxed and happy about it,'' my father had said and I'm amazed, looking through this window into the past, by just how unfazed I do seem to have been by it all, how I was not in awe of this man whose work I worshipped so. ''With great affection" indeed!
For darker times would come when I was not at all relaxed - an era I would explore in my novel Candy: A Novel of Love and Addiction. And the fact that I still have the cards and letters is closely related to an extraordinary sequence of events that occurred much later.
When I was 19 or 20, studying arts at the University of Sydney, I knew a couple of the editors of Honi Soit, the student newspaper. A young cartoonist, David Messer, was fooling around with Tintin ''mash-ups'' on the back page - taking strips from the existing books (I dare say illegally) and morphing some of the dialogue and pictures, making Tintin not just a young adventurer but seemingly an adventurer-cum-drug- addled rogue as well. At some point, I must have lent him the cards and letters - and promptly thought no more of the loan. Extraordinary though this seems to me now, I remember only that I was heading towards the precipice over which would lie years of chaos.
Jump forward seven or eight dark, demented years and life had finally collapsed into the heap it was always going to collapse into. I was discharged from the Langton Centre, a detox facility in Surry Hills, and told I had to wait three days for an available bed in the rehab program into which I'd been accepted.
The catch was, you could only enter the rehab directly from the centre. They said they would make an exception for me but only if I stayed at the house of someone who was in recovery. (I knew very few such people.) Through a friend of a friend, I found a sofa I could crash on for the weekend - at the house of a woman, a few years clean, who had a 12-year-old daughter and three-year-old son.
I was three weeks off drugs for the first time in nearly a decade. Life seemed hallucinatory, raw, bewildering. Mostly what I remember is craving milk. Everything was about to change and I had absolutely no idea what that meant or what it would feel like. There were a few Tintin books in the bookshelves in the living room.
''I was so into him as a kid,'' I said upon seeing the books. ''You know, I even wrote to the author and he sent me all these letters and cards.''
My host replied: ''Oh wow, you should see what we've got.'' She took me to her daughter's room and pulled out a filing box.
And there - unthought of for eight years - was my Hergé´ trove. After the first moment of incomprehensibility, after my jaw dropped, after the flush of goosebumps - after I almost fell to my knees - I stammered: ''These - these are mine. You found my letters!'' She thought I was joking; why would you not? ''Look.'' I pointed to the envelopes: every one of them addressed to Luke Davies. ''Where did you get these?''
What had happened was, a couple of years after I'd given the packet to David Messer the cartoonist, a new Honi Soit editor had been clearing out old junk from the newspaper offices and had come across the cards. He thought they were an interesting curio, and held on to them. As it turned out, this fellow was a friend of the woman I stayed with that fateful weekend, and at some point, when her daughter was eight or nine, he'd noticed that she liked Tintin and had given her my cards and letters as a gift.
It was all so improbable, so exhilarating, the letters' journey through the years and back full circle to me. The fact that deep in the stranger's house, like an amulet in some fairytale, would be my long-lost letters; the fact I even noticed a stray Tintin book in a bookshelf.
It is as if at that moment my old life - that innocent boy - was being given back to me in the form of a new life; and everything in between was wiped clean. (Historical fact: it wasn't, technically speaking. Oh, the wreckage. Oh, the clean-up operation.)
The author of Where the Wild Things Are, Maurice Sendak, once related the following anecdote.
''A little boy sent me a charming card with a little drawing on it. I loved it. I answer all my children's letters - sometimes very hastily - but this one I lingered over. I sent him a card and I drew a picture of a Wild Thing on it. I wrote, 'Dear Jim: I loved your card.' Then I got a letter back from his mother and she said: 'Jim loved your card so much he ate it.' That to me was one of the highest compliments I've ever received. He didn't care that it was an original Maurice Sendak drawing or anything. He saw it, he loved it, he ate it.''
I relate to that little boy's ritualistic, proto-religious ingestion, his desire for total communion with the Other, for that which has given him joy. It's a magnificent moment in obsessive fandom.
But I'm very glad that by nine years old I had a more sophisticated sense of what to eat, and what to leave alone.
Luke Davies is a poet, novelist and screenwriter. His latest book is Interferon Psalms. The Adventures of Tintin opens on Boxing Day.