The Sheldonian Theatre is one of the many places where the walls between Lyra's Oxford and our own seem particularly thin. This became even more apparent last night, when the theatre was packed out by an audience eager to listen to two towering children's authors, Katherine Rundell and Philip Pullman, speaking about writing.

Chaired by the Guardian's Sian Cain, the evening opened with a discussion of the responsibility an author has to their story - to protect it, parent it, and let it find the shape it needs to have, before sending it out into the world. This idea of stories as a living entity - almost like the daemons that form such a central part of Pullman's His Dark Materials - was returned to throughout the night, with both authors talking about their writing processes and all the complex feelings that surround them.

Rundell talked about the 'terror' of turning over a new manuscript - a strong contrast to the fearlessness she demonstrates in her research. For her latest novel, The Explorer, she travelled to the Amazon, trapped spiders and piranhas, and made all of the food that she describes in the story. (She couldn't quite bring herself to eat a local delicacy - tarantula - during her visit, but corrected this when she came home, telling a hilarious story about buying a tinned spider from Selfridges and discovering that, despite what she'd been told, it didn't taste anything like prawns).

The evening was full of similar funny and vivid anecdotes, and it was clear that the two authors had the utmost respect for each other and their work, despite their vastly different approaches (far from venturing to the Amazon, Pullman commented that he found it irritating to even have to go so far as Kidlington - the Arctic of His Dark Materials comes courtesy of the Bodleian).

Taking writing and stories as a central focus, the discussion moved around a huge range of topics - the current difficulty new writers have making a living, the wrong-headedness of pressuring children to read the "right" books, and what makes children's stories special. The conversation was absorbing - I forgot all about the crowd and the Sheldonian's notoriously uncomfortable seats while I listened, and clapped along with the rest of the audience when Pullman made especially pithy points about the need for more books in schools.

The night rounded off with fairy tales - Pullman talking about them as a source of inspiration, and Rundell focusing on the delicious darkness of some traditional stories. The audience questions were enthusiastic, showing just as much love for stories as the authors had - and when Pullman revealed to Rundell that baby daemons are named by the daemons belonging to their human's parents, an audible "Aw!" rippled around the room.

Sadly, I had to skip the book-signing after the talk, but I left the Sheldonian with my head full of snippets about stories and writing that I spent the rest of the night turning over in my mind. I'm looking forward to returning to His Dark Materials, and starting The Explorer - although I think I'll leave the tarantula-eating to the experts.