I realised today it has been more than 21 years since I first came across Terry Pratchett. I was only 12 at the time; young, gawky, bookish.

His books were like the opening of a window.

Pratchett is the creator of the epic Discworld fantasy series. They started off as a light-hearted send-up of the swords-and-sandals fantasy epics of Beowulf and Tolkien. Then they became an original world.

It is one of my annual joys. This year, when Making Money came out I chortled with joy and phoned one of my best mates to gloat that I’d got it first. Instead he turned the tables on me to say how much he’d already enjoyed it.

Pratchett is a prolific writer, having been first published at age 15, having his first big hit in 1971 with The Carpet People, and creating the first Discworld book – The Colour of Magic – in 1983.

For 21 years I have loved every moment of his books. As I finish my first read of a new saga I turn straight back to page 1 and begin again. Somehow – and books are frightfully expensive in South Africa – I have ensured that I’ve read and bought every one of them.

Today there is no laughter. Today there is tremendous sadness.

Terry Pratchett announced on Tuesday that he has been diagnosed with a rare form of Alzheimer’s Disease. His approach, like his approach to life, is light-hearted. In a release titled An Embuggerance he states his case. “Frankly, I would prefer it if people kept things cheerful, because I think there’s time for at least a few more books yet,” he says. And he’s perfectly correct.

“PS I would just like to draw attention to everyone reading the above that this should be interpreted as ‘I am not dead’. I will, of course, be dead at some future point, as will everybody else. For me, this maybe further off than you think – it’s too soon to tell. I know it’s a very human thing to say “Is there anything I can do”, but in this case I would only entertain offers from very high-end experts in brain chemistry.”

However, I can’t help feeling incredible pain at the unfairness of it. Alzheimer’s is a living death and I can’t see how anyone, least of all such a nimble and inspiring mind as Pratchett’s, can “deserve” such a fate.

Anyone who wants to see the maturing of a writer, the creation of deep and subtle characters, and a person who gets deep inside the skin of his stories should read Pratchett. Because his motif is fantasy he tends to be discounted by the literati yet you will search far before finding someone with as good a sense of plot-pacing.

He is also one of the finest writers of female characters. From his witches, to Monstrous Regiment (a war book about a troop of women), to the more recent series of teen books on the education of a young witch.

He has always been my guide as to how a writer offers a moral judgement without preaching or removing the reader’s free choice.

I have been intending to feature Pratchett in Scroguely Works for some time. Finding a favourite favourite has always been the difficult one.

For the next few years, as long as he is able to keep writing, I will come to each new book with reverence and apprehension. I will treasure each new word and savour each new story.

Perhaps this is the most important gift he can give me, or any of his readers; the knowledge that life is precious and genius is a rare treasure to be recognised and appreciated.

When that day comes that Pratchett’s sands run out, I hope that the Death who cuts the thread of his life is wearing a cowl and does so with a scythe. And that Death embraces him as the caring friend that he is and takes him away into the next life on a white horse called Binky.