Andrew Motion: Why I chose to speak of God in the simplest words

My new poem, published here for the first time on the eve of Lent, takes its cue from St John's gospel, which has long been the one that means the most to me. It has such an extraordinary factual interest, combined with the quality of the writing. When I read the gospel again I found I had forgotten two things. I'd forgotten that John tells us how many fish were caught after they had cast their nets out of the other side of the boat. He doesn't just say a lot of fish, which is how I'd remembered it, he says 153 fish. Then later he mentions that there was a fire on the beach, which I took to be a kind of barbecue.

Those two details struck me powerfully because this story is profoundly to do with transcendence but in its midst, we have these two very beautiful, practical, humanising and, in a sense, earthing details. Those two things were really the trigger for the poem. We have only to look at an open fire to see the structure of the air being changed - that strange, shimmering, buckling effect, rather like the expectation you might have if you were seeing somebody neither quite obviously of Earth nor of the world beyond, but in an in-between state.

The poem is partly about bereavement and loss. It is also about wanting to reassure yourself at moments of uncertainty. These are recently bereaved people, the disciple fishermen. And they're also people who have lost a great shaping force in their lives, the greatest philosophical, emotional, everything force in their lives. This is not a force of the usual kind, in the sense that there has already been a good deal of talk about the after-life and heaven and associated things. So when they say: "Master, don't go", it's just not just that they are people grieving as you and I might grieve - but also I hoped to register a special kind of plaintiveness; the sense that they are saying, "Don't go, because if you do go completely that will throw us into confusion about what we're beginning to understand about heaven."

The idea of the title was to say that this is a poem written in the simplest kind of language that I could manage but it is about a perennially, highly complicated thing - faith. As the poem says, they went out, expecting to catch something - and quickly came to believe they weren't going to catch anything at all. And then, after Christ had intervened, they caught so much that they didn't know what to do with it. So what the poem is really seeking to say is that the promise of heaven is manifest to them in the catching of all those fish. But the prospect - though profoundly welcome - is also rather bewildering. Their faith has been validated, but to a slightly confusing extent by the prodigious number of fish they have caught.

My own faith, as no doubt I'll be saying when we make the programme, is something which comes and goes rather; so I suppose that fits into the general shape of the poem. When I am able to feel it - and it's something that I would very much like to feel more regularly, more fluently - I do sometimes feel bewildered by the richness of the promises it appears to make and keep. So the oscillations of the poem between nothing and too much are not quite the oscillations between bleakness and total congestion but between comparative bleakness and a promise which is so enormous in its richness that it is bound to be bewildering.

Andrew Motion, the Poet Laureate, will read 'Simple' during 'What the World Thinks of God', BBC2, 9pm on Thursday.

Simple

Men came from the sea

with their unusual catch -

one hundred and fifty three.

A fire burned on the beach.

They had expected nothing,

now there was a glut,

and also this man waiting.

The charcoal was white hot.

But was the man there?

One moment it seemed so,

the next he was not.

Master, they said, don't go.

Like thin air shimmering

when powerful heat bakes it,

he continued his waiting.

Indefinite. Definite.

The fire burned on the beach

with their unusual catch.

They had expected nothing.

Now there was too much.