Travelling in a jam-packed metro affords a useful guide to people’s reading habits. They’ve changed over the past decade: I notice fewer men reading fiction than I used to – and the number reading what is termed "literary fiction", never large, seems to have shrunk to zero, especially among young men. You’ll see more hen’s teeth on the train than millennial men reading Ian McEwan or Jonathan Franzen.

The genre that men now seem to be reading more than any other is what you might call "ideas". By a country mile, the author I’ve seen most men bury their nose in recently is Yuval Noah Harari, author of Sapiens: A Brief History of Humankind and Homo Deus: A Brief History of Tomorrow. Coming close behind are Yanis Varoufakis (Talking to My Daughter About the Economy: A Brief History of Capitalism) and the clinical psychologist Jordan Peterson (12 Rules for Life: An Antidote to Chaos).

Women still seem to favour novels, but genre fiction seems to be supplanting literary fiction in their affections, and I’ve seen more and more younger women readers gripped by Sapiens and the like, too.

My unscientific observations are supported by a few facts. In 2019, it was reported that sales of non-fiction had grown by nearly 30 per cent in the previous five years.

By contrast, a British report a couple of years ago found a drastic decline in sales of literary fiction was throwing many authors into penury. So, as P G Wodehouse might have put it, challenging non-fiction is booming while challenging fiction is down in the basement with no takers.

So, why are we all ideas men and women now? It’s partly because publishers have become more confident that the general reader is interested in ideas.

Stephen Hawking’s A Brief History of Time, turned down by four publishers before it became a bestseller in 1988, showed that it was worth investing large chunks of the marketing budget in the likes of Richard Dawkins and Stephen Jay Gould.

One game-changer was the Penguin Great Ideas series, published between 1995 and 2010. This was a series of 100 volumes, covering a huge historical and geographical range.

Many of the books were very successful. A small collection of Ruskin’s essays sold 70,000 copies. George Orwell’s essays, which Penguin Books had not previously managed to turn into a money-spinner, sold 140,000 copies when repackaged into the Great Ideas format.

Why were they so successful? The books were beautifully designed. They were appealingly short, and portable (when are publishers going to notice that the decline in numbers of men reading has coincided with the average paperback becoming too big to fit in a pocket?).

But also, as Simon Winder, the mastermind behind the project, put it, the scheme was successful because Penguin tried to publish the books "in a form close to that recognised by the book’s original author – to strip away the accretion of prefaces, introductions and notes".

Academics so often get in the way of books from the past, pretending that they need endless explication for modern readers to understand them.

The Great Ideas series has helped to rescue ideas from the Professor Dryasdusts for the benefit of the general reader, and remind us that the classics of philosophy, science and criticism can be as thrilling and immediate as fiction. The good news is that, after a decade’s hiatus, the Great Ideas series returned recently with the publication of 20 new volumes, ranging from Aristotle to Martin Luther King.

At this rate, the series will soon encompass every great idea in history bar the one Michael Caine has at the end of The Italian Job.

I must say, though, that two items in the news recently have put a slight dampener on the pleasure that the return of Great Ideas has brought me. One was the decision by Edinburgh University to rename its David Hume Tower because Hume (1711-76) had racist views.

The other was that Rada is considering dropping Bernard Shaw’s plays from its curriculum because of his eugenicist enthusiasms. Two sad thoughts occur to me.

First: Great Ideas celebrates controversial breakthroughs in thought that now seem like commonplaces, and tries to make us see them afresh.

Yet one wonders, in our hysterically censorious times, how many thinkers are opting for a quiet life rather than expressing their heterodox ideas.

This does not bode well for the future of our current non-fiction boom: how many "Great Ideas" from the 2020s will be celebrated in 100 years?

My second worry is that people are now being led to think that writers from the past are irrelevant. If they read about the denunciation of Hume’s racism, will they want to tackle Number 34 in the Great Ideas series – Hume’s On Suicide, a beautiful piece of work that eloquently expressed so many of the arguments of the modern "Right To Die" movement 250 years before it got started?

The Great Ideas series strikes a good balance. It has increased diversity – there are six books by female authors in the new batch, which is as many as there were in the previous 100, and a quarter are by authors of colour. But it makes room too for Nietzsche (arguably racist and proslavery) and Oscar Wilde (predatory sex pest).

But when the next batch of authors are chosen, will the publishers be brave enough to choose authors whom young people are turning against?

Darwin and Winston Churchill have featured before, but both have recently been accused of racism, and the Natural History Museum is reviewing exhibitions based on Darwin’s "colonialist scientific expeditions".

Will they be allowed to return to Great Ideas if the target market thinks they’re wicked or, at best, irredeemably outdated?

Cancelling the living because you find their views offensive is inane, but cancelling the long dead defies logic. In the present climate, more and more thinkers from the past are vanishing from view because some of their beliefs are at odds with our own.

This is near-literal narcissism: we only want to see ourselves reflected in what we read. And if we refuse to engage with writers from the bad old days – i.e. most of recorded history – we lose something inestimably precious.

The titles from the Great Ideas series, published by Penguin Classics, are available now in e-book and paperback.

The Daily Telegraph

Read more