He has researched, wondered and worried a great deal about appropriate ways in which to present the horrific experiences of survivors of the Holocaust and other atrocities, and also how to convey those to young readers.
He said several times that he felt that he had no right to give voice to that experience: he has no survivors in his family and is not Jewish.
"I am glad I made the decision not to pretend ..." he said.
"Pretend." Not "imagine", but "pretend", as if it would somehow be a more artificial process than his normal creative practice.
It reflects Kate Grenville's statements about the decisions she made about portraying Aboriginal characters in The Secret River:
I'd always known I wasn't going to try to enter the consciousness of the Aboriginal characters. I didn't know or understand enough - and I felt I never would... Their inside story - their responses, their thoughts, their feelings - that was all for someone else to tell, someone who had the right to enter that world and the knowledge to do it properly. (Searching for the Secret River)
But as Inga Clendinnan has pointed out, Grenville does believe she has the right to enter the consciousness of a whole range of other characters whose world - two hundred years ago on the other side of the planet - is arguably as alien to her modern urban life as any other.
I also remember a session at the Melbourne Writers' Festival about a million years ago, in which somebody - a woman - argued that male writers ought not attempt female characters because they are incapable of correctly perceiving and portraying the female experience. Another panellist - it might have been Garth Nix - extravagantly suggested the use of imagination.
One might also have added the crazy concept of extensive research.
John Boyne, of course, is selling himself short. He has imagined and created a vision of the concentration camps, albeit from a naive bystander's point of view.
But Kate Grenville's decision not to portray Aboriginal characters has an unfortunate effect quite opposite, I feel sure, to her intent. It leaves a gap in the consciousness of the reader - a hole where the indigenous experience should lie. Indeed, it means that there are no real defined Aboriginal characters in The Secret River at all. So does that force the Aboriginal people - the dispossessed of the Hawkesbury River - to once again become inexplicable fringe dwellers on the edge of the action, until, of course, they become the sudden centre of attention as they are massacred?
After all, how does a writer get into anyone's skin? How does Grenville imagine her character Thornhill, his hard hands on the oars as he sculls against the Thames tide? How does John Boyne imagine the boy Bruno sitting by the wire?
What gives them the right to imagine those experiences and not others? Does someone somewhere grant these rights? Or do we each have our own internal boundaries that we feel we can't cross? And how do we know?
I'd much rather have writers like Boyne worry about transgressing those boundaries than blindly push on regardless of cultural or other sensitivities. It'd be only too easy to assume that you could dream up anything and get it terribly horribly wrong. Especially, as Boyne suggests, with the benefit of many layers of privilege.
But surely writers have the right to imagine.
There are no rules.
Sometimes you might decide you can't possibly imagine this or that - a horrific experience, an inner life, a cultural background, a sound, a voice, an entire character.
You might do it badly or wrongly.
But that's a failure of imagination - it's a totally different thing to not being allowed.
Nobody has to seek permission to imagine.
When? Why? And from whom?