A friend recently pointed out to me that artists of all kinds often make their discoveries early in their working lives. Writers, painters and musicians, he suggested, frequently know what they want to say and how they want to say it by the time they are 30. The rest of their careers are then spent refining these initial discoveries.

It's an idea that has a great deal of truth. Look at the retrospective of Francis Bacon that has just opened at Tate Modern, and you see an artist who discovered as a relatively young man a small but resonant set of images that spoke to him. He then refined this personal iconography over decades. Major events in his life may have rearranged the furniture a little, but the twisted bodies in the little rooms remain essentially the same.

Samuel Beckett is perhaps the starkest example of a writer whose work was not about discovering new perspectives as he got older, but about refining his vision; his diminishing word count is evidence of this. After emerging from the shadow of Joyce, Beckett moved from the novel to the theatre, and his theatre work gradually became shorter and sharper. The four rootless adults, the boy and the tree in the two-act Waiting for Godot, seem recklessly extravagant compared with the stark images of his later work: the isolated, babbling mouth in Not I, the brief glimpse of litter and the sound of exhalation that constitute the tiny play Breath.

Great artists such as Bacon and Beckett distil; lesser artists become self-referential and self-conscious as their work goes on. A personally defined landscape can easily become an enclosed and introverted prison, referring only to itself.

I like to think I'm open to new experiences and new ways of writing, even though I am now, by anyone's definition, middle-aged. It gets harder to encounter new people and new experiences as you get older - not just for artists, but for all of us. The wide network of friends that I moved in as a young person has now become a handful of familiar faces. When I was in my 20s I worked in the laundry of a mental hospital, a building society and a drug rehabilitation centre. Now I sit at a desk all day and write.

Whenever a novel starts with the character of a writer sitting in a Hampstead kitchen, struggling to finish a novel, I throw the book straight in the bin. I recognise where that impulse to write about writing comes from. From time to time, I find myself thinking of ideas for plays about screenwriters working in Hollywood, or actors putting on a play. This terrifies me. There has been some great writing about writing, terrific films about films, brilliant television about television. There's an inevitability about the fact that Ricky Gervais began by telling us stories about an ordinary workplace (The Office), and then, once he was massively successful, moved on to stories about showbusiness (Extras). But this seems to me something of a dead end. If it's a struggle to stay connected to the world as you get older and more established, I think it's worth it.

It's not as though the outside world isn't ready to embrace artists. Recently, I ventured out into north London with a group of young actors, stopping Camden market-goers and asking them about their lives. We started nervously, assuming that approaching strangers with the opening line, "Hello, I'm a writer and this is an actor and we're researching a play," would meet with a frosty response. But almost everyone wanted to talk to us, often at great length. We were humbled by the way many of these people told us deeply personal and often painful things about their lives. We came away with a great sense of responsibility for the complex and difficult insights into other existences we had been given, often within minutes of meeting people.

No doubt a Freudian would tell me that the outside world only reflects back to me my own inner conflicts. They may be right: work that seems objectively researched when I'm writing it is often surprisingly autobiographical when I look back at it later. Still, I remain committed to seeking new experiences to inform my writing. If you'd like to invite a writer to your factory, or mosque, or family get-together, please get in touch. Kafka once advised writers to sit in a room and wait for the world to reveal itself to them. Right now, I'd rather get out and explore.