We are in a large, white-walled room on the green at Somerville College, Oxford. At one end of the room are a philosopher, a poet, and a battered biscuit tin. A small audience is listening to a discussion, mixed with poems, on whether humans are more like separate billiard balls or organic parts of a larger whole. Sun is streaming through the windows.

I’ve come for the biscuit tin. Or, to be more accurate, for the previous owner of the biscuit tin: Mary Midgley. She was perhaps Britain’s leading public phil­osopher until her death at 99 in 2018. The meeting at Somerville College – where she studied and where she met her lifelong friend Iris Murdoch – is part of celebrations for Midgley’s centenary year. It’s one stop on a round-the-world tour with a twist.

When she left Newcastle University’s philosophy department at 61, Midgley was a little-known author of a single book. Retirement was the best career move she ever made. By the time of her death, she had published 18 books with titles like Animals and Why They Matter, Science and Poetry, and Myths We Live By, and over 200 articles in New Scientist, The Guardian and Philosophy Now. Her work on the origins of human nature and the need for a holistic understanding of the sciences has been praised by the Financial Times as “commonsense philosophy of the highest order”. With her death, Britain lost a unique voice.

Like plumbing under the floorboards, most people ignore philosophy until something begins to stink. This was Midgley’s favourite metaphor. She put herself to the task of digging up and straightening out the twisted pipes and blocked drains of human thought. In clear writing for the general reader, she came back time and again to the biggest stink of the day: our suicidal attitude to the natural world. And to the end, she never gave up.

Her last drain unblocker – What Is Philosophy For? – was published three weeks before her death. She wrote the book in exasperation, she said, with “the whole reductive, scientistic, mechanistic, fantasy-ridden creed which constantly distorts the world-view of our age”. For someone who championed cooperation, she knew how to fight.

Midgley’s most famous public clash was with evolutionary biologist Richard Dawkins. In the 1980s, she exchanged angry articles with the wildly popular Selfish Gene author. Dawkins accused Midgley of raising “the art of misunderstanding to dizzy heights” and wrongly claimed she had not read his book. Midgley, in turn, said essentially that Dawkins had misunderstood Nature, and branded his version of evolution “biological Thatcherism”.

What keeps me coming back to Midgley’s writing is the breadth of her vision, her refusal to reduce the rich, complex world to simple answers, and her passion. I wish that she more often looked beyond the western tradition, but I love her fascination with stories – especially the ones so big that we don’t recognise that we are living in them.

While many turned away from the New Age associations of James Lovelock’s Gaia theory, Midgley celebrated it as “the next big idea”. The idea of the Earth as a self-sustaining natural system, she argued, opens us up to an appropriate “reverent, awe-struck attitude” to our total dependence on Nature. Gaia shows us that we are at home in the world. We are not tourists here.

But what does all this have to do with a travelling biscuit tin? For decades after her retirement, Midgley hosted friends and visitors in her home in Newcastle every week for discussion evenings. Her philosophy was a community, not a solo endeavour. Inspired by the “wit, wisdom and ginger snaps” Midgley dispensed, Rachael Wiseman and Clare Mac Cumhaill, two younger philosophers, organised the biscuit tin tour.

The tin – a gift from the Midgley family – is travelling to twelve locations over 12 months, taking in Tokyo, Sydney, and Paris. At each stop, a poet and philosopher will discuss one aspect of Midgley’s work: Art, Language, or Myth. The journey is due to end at the Durham Book Festival in October 2020. The contents of the tin, including a poem commissioned for each stop, will be delivered to Midgley’s archive in the city. The emphasis on poetry is not random.

Midgley liked to say that great thinkers need to combine the analytical skills of the lawyer and the imaginative vision of a poet. Sadly today, Wiseman and Mac Cumhaill, now at Liverpool and Durham universities, write, “the system of academic philosophy – at least in the UK – weeds out the poets and leaves behind only the lawyers.”

As well as thinking like a poet and a lawyer, Midgley was at times an activist. She marched against apartheid with her young sons and was even once arrested. It was the 1980s, and on the way to see Iris Murdoch she stopped at a nuclear disarmament protest at a US military base in Oxfordshire. As she was standing by the gate, the military convoy started moving through it. According to one version of the story, she had no idea what to do, so she sat down in the road and stopped the convoy. The police arrested her and took her away. She got off with a court appearance and a small fine.

Back at Somerville College, after the discussion, the white-walled room humming with chatter, the chink of cups on saucers, and the subtle crunch of chocolate biscuits, I spoke to Erin Kavanagh, a philosopher and artist from Wales, and asked her why anyone should care about Midgley’s work today. “Mary Midgley was writing about tomorrow 40 years ago,” she told me. “The things that she set out so clearly are happening now, with Extinction Rebellion.”

We cannot know for sure what the 100-year-old philosopher would have thought about XR. But her son David says she would have been behind the protests: “I am quite convinced that she would have been fully prepared to stand in front of the vehicles coming out of the gate for that cause [too].”

See updates to the schedule at notesfromabiscuittin.com

Nat Dyer is a writer and former anti-corruption campaigner based in London @natjdyer