Though English was the language of my parents, the language in which I was raised and schooled, I have never felt I belonged to it. I learned my mother tongue self-consciously, quite often confusedly, as if my mother were a foreigner to me, and her sole language my second. Always, in some corner of my child mind, a running translation was struggling to keep up. To say this word or that word in other words. To recompose the words of a sentence like so many pieces of a jigsaw puzzle. Years before doctors informed me of my high-functioning autism and the disconnect it causes between person and language, I had to figure out the world as best I could. I was a misfit. The world was made up of words. But I thought and felt and sometimes dreamed in a private language of numbers.

In my mind each number had a shape – complete with colour and texture and occasionally motion (a neurological phenomenon scientists call synesthesia) – and each shape a meaning. The meaning could be pictographic: 89, for instance, was dark blue, the colour of a sky threatening storm; a beaded texture; and a fluttering, whirling, downward motion I understood as “snow” or, more broadly, “winter”. I remember, one winter, seeing snow fall outside my bedroom window for the first time. I was seven. The snow, pure white and thick-flaked, piled many inches high on the ground, transforming the grey concrete of the neighbourhood into a virgin, opalescent tundra. “Snow,” I gasped to my parents. “Eighty-nine,” I thought. The thought had hardly crossed my mind when I had another: “979”. The view from my window resembled 979 – the shimmer and beauty of 11 expanding, literally multiplying 89’s wintry swirl. I felt moved. My parents’ firstborn, I had been delivered at the end of a particularly cold and snowy January in 1979. The coincidence did not escape me. Everywhere I looked, it seemed, there were private meanings writ large.

I read lollipop as 1011ipop: 1011, divisible by three, was a fittingly round number shape, a most beautiful thing

Was it from that moment – the sudden sense that my meanings corresponded to the wider world – that I first had the urge to communicate? Until that moment, I had never felt the need to open up to another person: not to my parents or siblings, let alone to any of the other children at my school. Now, suddenly, a feeling lived in me, for which I had neither name nor number (it was a little like the sadness of six, but different). I eventually learned the feeling was what we call loneliness. I had no friends. But how could I make myself understood to children from whom I felt so estranged? We spoke differently, thought differently. The other children hadn’t the faintest idea (how could they?) that the relationship between 89 and 979 was like the relationship between, say, diamond and adamant. And with what words might I have explained that 11 and 49, my mental logograms, rhymed? The children at school intimidated me. In the playground every mouth was a shout, a snort, an insult. And the more the children roared, the more they laughed and joked in my direction, the less I dared approach them and attempt to strike up a conversation. Besides, I did not know what a conversation sounded like.

I renounced the idea of making friends. I had to admit that I wasn’t ready. I retreated into myself, into the certainties of my numerical language. The same understanding, the same excitement, also helped me learn to read. This was my luck, since reading had not initially come easily to me. My parents never read me bedtime stories, and because the anti-epileptic medicine I was prescribed at a young age made me drowsy in class, I was never precocious. I have memories of constantly falling pages behind the other children, of intense bouts of concentration in order to catch up.

Back in those days, the mid-80s, it was possible for a teacher to give her young charge a repurposed tobacco tin (mine was dark green and gold) in which new words, written in clear letters on small rectangular cards, were to be brought home for learning. From that time on I kept a list of words according to their shape and texture: words round as a three (gobble, cupboard, cabbage); pointy as a four (jacket, wife, quick); shimmering as a five (kingdom, shoemaker, surrounded). One day, intent on my reading, I happened on lollipop and a shock of joy coursed through me. I read it as 1011ipop. One thousand and eleven, divisible by three, was a fittingly round number shape, and I thought it the most beautiful thing I had yet read: half number and half word.

In writing the story of my formative years in the words I had back in 2005 (I was 26), with feeling but without confidence or high finish, I found my voice. The international success of Born on a Blue Day began a conversation with readers from around the world. Where some British and US critics saw only a one-off “disability genre” memoir, the account of a “numbers wiz”, German and Spanish and Brazilian and Japanese readers saw something else, and sent letters urging me to continue writing.

The numbers spoke through the printed page to my far-flung readers, came alive in their minds, regardless of the translation that conveyed them. My lifelong struggle to find my voice, my obsession with language, appeared to them, as it did to me, like a vocation.

I’d written a book and had it published. But it remained unclear whether a young man on the autistic spectrum could have other books in him. No tradition of autistic writing existed (indeed, some thought autistic author a contradiction in terms). I had no models (though, later, I made the discovery that Lewis Carroll – possibly – and Les Murray, the Australian poet and Nobel prize candidate, to name only two, shared my condition), no material. I was on my own.

All literature, I finally realised with a jolt, amounted to an act of translation

But then another reader’s letter arrived. It was in French, a language I had studied in high school, from a young Frenchman named Jérôme, who would, in time, become my husband. Through months of thoughtful and playful correspondence, Jérôme and I fell in love. For him, for his country and language, I chose willingly to leave the country and the language I had never felt were mine. We moved to Avignon, then north to Paris, settling among the bistros and bouquinistes of Saint-Germain-des-Prés.

Before Jérôme, I had largely given up on literature. Novels and I had long since parted company. Now, though, in our apartment, surrounded by our books (Jérôme owned many books), we sat together at a brown teak table and, taking turns, read aloud from the French translation of Dostoevsky’s The Idiot. Reading a Russian work in French, I was not invaded by the feeling of foreignness that the pages of English novels had roused in me. On the contrary, I felt at home. I could, at last, read unencumbered by my self-consciousness, solely for the pleasure of learning new words and discovering new worlds. I could read for the sake of reading.

Something had worked itself out in my head. All literature, I finally realised with a jolt, amounted to an act of translation: a condensing, a sifting, a realignment of the author’s thought world into words. The reassuring corollary – reassuring to a novice writer like myself, just starting out: the translatorese of bad prose could be avoided, provided the words were faithful to the mental pictures the author saw. I had more than one book in me. And each of my subsequent books – a survey of popular neuroscience, a collection of essays inspired by mathematical ideas, a translation/adaptation into French of Murray’s poetry – was different. Each taught me what my limits weren’t. I could do this. And this. And this as well. All the time that I was writing, I was also studying in my after hours with theUK’s distance learning higher education institution, the Open University. In 2016, at the age of 37, I graduated with a first-class degree in the humanities. I published my first novel that same spring in France.