If during the 80s and 90s you were any kind of book lover, Milan Kundera – who died this week aged 94 – was one of that small clutch of modern novelists you absolutely had to read. In the late stages of the Cold War, the Czech-born Kundera not only gave us news about what was happening on the other side of the Iron Curtain – how those brought up under communism joked, suffered, survived and made love – but his irony and playfulness, oddly hard-nosed, caught the spirit of the times. To read him as a teenager was in many ways to be wrenched into adulthood and realise there were other countries, other ways of seeing – in fact, quite different moral systems – beyond your own. So many of us fell under his spell and have never quite emerged from it.

Reading Unbearable Lightness for the first time, you feel all your certainties shatter

It was the Unbearable Lightness of Being (1984) almost everyone started off with, his breakthrough novel about the lives, loves and interior philosophies of four different characters during the Prague Spring of the 1960s and its subsequent, monstrous crushing by the Kremlin. This story of Czech surgeon Tomáš, a man caught between two different women and the alternating life-poles of lightness and heaviness, had an insidious lyrical power and was rarely the last book of Kundera’s you read.

As a story The Unbearable Lightness of Being is relatively plotless, and certainly no thriller. A man dedicated to irresponsibility meets a younger woman, Tereza, at a provincial spa. He agonises about inviting her into his life but finds that the power to decide has been taken from him: his independence is gone. His mistress Sabina – a free-living and sexy painter – is aghast at Tomáš ’s new love, but being a sophisticate embraces them both, along with a married Swiss academic named Franz. As the Soviet tanks roll into Prague, taking away Czechoslovakia’s freedom just as Tomáš loses his, the four of them disperse, though not all are able to tear themselves away from their benighted country, and they end up…

Well, read the book. But what matters isn’t so much the story as the cocktail Kundera mixes – a blend of philosophy, music, psychological analysis and Central European history, bloodstained, pulverised and never boring. The book is also, on its own worldly terms, highly romantic, with much to say about love. ‘Making love with a woman and sleeping with a woman are two separate passions,’ Kundera tells us, ‘not merely different but opposite.’ Love does not make itself felt in the longing for sex (you can enjoy that with numerous partners) but ‘in the desire for shared sleep’, limited to just one. Tomáš’s epic philandering, colourfully described by Kundera, endures, but so does his love for the delicate Tereza who, seeming sent to him by fate, enters his soul for good. ‘Metaphors are not to be trifled with,’ warns Kundera. ‘A single metaphor can give birth to love.’

Reading Unbearable Lightness for the first time, you feel all your certainties shatter. In Kundera’s world characters can love cruelty more than kindness; can relish treachery yet retain a reader’s faith; can love deeply and tenderly and yet stamp on that love. Every value of ‘good behaviour’ – the things your parents and teachers taught you – comes under attack. What is loyalty? Perhaps something heavy and predictable, even a force of death. What is betrayal? At times a breaking of ranks, an optimism, a faith that what you have can always be improved.

At the centre of this is Kundera’s Sabina, surely one of the most complex and interesting characters in modern literature. It’s Sabina, with her apparent amorality – but fierce ethical stance against the sickly-sweet lies of kitsch – who seems to interest him most. Sabina, with her addiction to betrayal and terror of encirclement, her private vocabulary and incommunicable secrets, her need not to be completely understood.  ‘The characters in my novels are my own unrealised possibilities…’ he writes. ‘Each one has crossed a border that I myself have circumvented.’

The book is finely balanced. When the suffocations of their personal lives threaten to overwhelm the characters – or us – there’s always Cold War politics, with its battering tanks, clear sharp lines, the selfhood of stark choices, to escape into. Part of the frisson of reading The Unbearable Lightness in 2023, with its description of the Soviet invasion, is how closely events mirror the dark, futile hopes Putin nursed for his own ‘special military operation’ in Ukraine. In ’68 Czechoslovakia capitulates. Its leader Dubček’s spirit is broken in Moscow. Possibly drugged he makes a rambling radio broadcast to the Czech people, when he is forced to crawl to the Kremlin’s authority: ‘Tereza would never forget those awful pauses in the middle of his sentences… Those pauses contained all the horror that had befallen their country.’ We see a Czechoslovakia with its street names obliterated and Russified with new labels: ‘Stalingrad street, Leningrad Street, Moscow Street…’  But characteristic of Kundera too are his descriptions of Prague’s young women taking, in their miniskirts, a ferocious ‘sexual vengeance’ against the invader. ‘The Russian soldiers had been kept in enforced celibacy for several long years.’ The girls ‘paraded their scorn on beautiful long legs the like of which had not been seen in Russia for the past five or six centuries.’

Big ideas and big events, personal and public, are explored in the novel’s 300 or so pages. It takes in – among many things – Nietzschean philosophy, the split between soul and body, the inner life of dogs and the precise underlying messages of a Beethoven quartet, the word ‘cemetery’, even a bowler hat. In the hands of lesser artists this would be overkill, yet the work is stripped down, injected with light and space, and always seeming to run to its own rigorous, clockwork design. Few writers burden you less, declutter more ruthlessly or are – to use a crude phrase – more ‘user friendly.’ Few are able to crystallise the thoughts you were only half-thinking, and take them with tantalising, almost feather-lightness to the moon.

Perhaps there’s no better way to finish, in the week of Kundera’s death, than the delightfully airborne lines he chose to end his novel with, as Tomáš and Tereza go to a cheap hotel room after a night of dancing at a country-inn:

 ‘Tomáš turned the key and switched on the ceiling light. Tereza saw two beds pushed together, one of them flanked by a bedside table and lamp. Up and out of the lampshade, startled by the overhead light, flew a large nocturnal butterfly that began circling the room. The strains of the piano and violin rose up weakly from below.’

A nocturnal butterfly, indeed. Safe journey, Mr Kundera. We’ll keep that lightbulb glowing some time yet.