As I write, I couldn't claim, quite, that my fingers are dancing across the keyboard. But they are making their way at a stately pace appropriate to my age (and figure), unimpeded by cramping of the limbs or brain. I enjoy writing for the Guardian, doing this occasional series of bibliobits, and am animated by my ongoing conversation with my readers.

At the same time, as I sit here at our house in New Zealand, I am trying to begin writing my next book, which is provisionally titled (in my mind, if not yet that of my publishers) The Life and Death of the Book. I have reason to feel cheerful, for I have another book coming out in April – Lost, Stolen or Shredded: Stories of Missing Works of Art and Literature – the publication of which will engender a lot of relief, as well as the usual anxieties.

As I began work on the new book, I wrote a yellow post-it and stuck it up over my desk: "Write as if you were writing for the Guardian. Make it fun." Because something that is fun to read – which is my hope with these occasional columns – is usually easier to write. If you bring a concentrated light-heartedness to the act of composition – even if you have to will it – you are, in my experience, more likely to write well, if not easily. Writing well is never easy.

Admittedly, the new book covers weighty ground, from cave art to Kindles (without being for a moment a "history of the book") and its many topics and obligations do not always flow trippingly off the pen. This problem is no doubt exacerbated by the fact that I am learning as I go along, but then again I like doing that, and believe that an author enjoying the process of discovery is often more agreeable to read than one mired in his or her own expertise. (One of the reasons I rather admire Geoff Dyer).

The new book is both more demanding and harder than burbling on about this or that for a column. But is it really all that different? Same me. Same (I hope) voice. Yet the differences are enormous, and the effects catastrophic. I arrived for my six weeks in New Zealand with the modest hope that I might produce, say, 12,000 words. Three hundred a day. Maybe a bit more, but acceptably and realistically perhaps a little bit less. But after three excruciatingly cramped weeks, whimpering at the keyboard every morning, I was unable to compose a single sentence as compelling, even, as the afternoon's shopping list. I could count 3,000 words, but they were faltering, joyless drivel.

I had to give it up. It was not merely making me miserable, but ornery as well. I railed against myself, was horrid to my very dear wife, was rude about New Zealand generally and Hawkes Bay (as close to paradise as you may find) particularly. Frustrated and depressed, I looked every day at my post-it sticker, until I pulled it down in a rage and binned it. "Fun?" What fun? It was as unmitigated as misery can get without a genuinely serious cause.

What went wrong? Aristotle says that a tragedy shows a good man declining from a state of happiness to one of misery, through a great error of judgment. I presume the tragic hero was, in his happy emotional state, writing a column, and in the miserable one a book – and that his error was in moving from the one to the other. Hence his downfall. He should have known better.

But we inhabit a world made up only transiently of columns and blogs, and more abidingly of books. It's no good, then, basking in the relative ease of the lesser endeavour, while shirking the more significant and difficult. Writing a good book, which is what one tries to do, is one of the great human activities, and if an author is good enough and lucky enough, the result will be around for generations.

Perhaps it is that thought that is so daunting? When I write one of these columns it flows off into the ether, people read it or they don't, make occasional comments, and then it is to all intents and purposes gone. It is to me anyway, though all of these pieces can still be found, and to a sensibility more contemporary than mine, presumably have the same longevity as a book.

But a book, a form that I both revere and fear, is another thing altogether. It requires more time, more research, more thought, more acute efforts of composition. It tests the authorial self severely, and consequently there is more at stake in its composition.

And reception. This may account for why authors are so unaccountably concerned with what the reviewers may say. Writers know that a review is simply the opinion of a person more or less fit to deliver a verdict. We are aware that, given that Joyce and Proust had their detractors, so may we. Yet our sensitivity to bad reviews can be so acute that, even if we do not entirely sympathise, we can understand Alain de Botton's response to a New York Times reviewer who had an adverse opinion of his new book: "I will hate you until the day I die."

But the fact that our work goes out into the world and gets publicly commented on doesn't seem enough, quite, to account for the anxiety that writing causes. The real concern, after all, is not what some damn reviewer or other may think, but quite simply whether the book is a good book. And though some authors are great praisers of their own products, most, I suspect, harbour an inward fear that the book is not, quite, good enough.

John Banville says that he does not read his reviews, not so much because it would be painful if they were slighting, but because he already knows – "better than any reviewer" – what is wrong with his books, the places in which he is painfully aware that they could have been better. Why read someone less likely to know where the sore spots are?

Writers, like all artists, are Platonists. We have an inkling of something perfect and ideal, which haunts our imaginings and prompts every stroke of the pen or keyboard. We are aware that with a great effort of attentiveness, formulating and reformulating, listening closely to our own voice, modulating it into more tuneful harmonies, we might do something not just good, but perfect. And occasionally in phrase or sentence or paragraph we do just that. But I know of no writer who is not, finally, just that little bit disappointed with the final product. (Well, I know some who are not, but they are never the good ones).

Maybe a "little bit disappointed" is mitigated by the further "but it is the best I can do". That's what writing a book demands of you. Whereas writing an occasional piece – such as this – isn't as daunting because one is not aiming for the unattainably perfect. I write this carefully, and as best I can, but mostly I am just having some (serious) fun, and hoping my readers are too.

So that's it, then. That's where the error lies. I cannot write the new book in the same spirit or voice as I write this column, nor should I have tried. Silly me. It is genuinely enjoyable to do these. Writing this book is harder, and worse, and better, and more important. And it requires, which is at the heart of the problem, that I keep my eye in different directions at the same time. Cross-eyed composition (looking at both the keyboard and my research notes) gives me a headache and makes me crazy, and is not conducive to an (apparently) effortless flow.

This seems a relatively flaccid conclusion: It's easier to write a column or blog than a book? Duh. You know that, and so do I. Or so did I. I seem to keep forgetting it, and need to remind myself every time I start a book. I never learn, keep sticking up those post-it notes, and then tearing then them down.

The fun comes later, once it the book is written. As long as the reviews aren't too bad…