WE ALL have favourite illustrations, in sermons, in lectures, even in conversation: images to which we return because they seem to sum up or embody the essence of what we are saying. The problem with these favourites is that they can become too familiar, and it’s helpful to revisit them or, better still, have someone else make us think them through again, lest they dwindle into unreflective cliché. I had just such an experience the other evening, after preaching at Trinity College, Cambridge.

I had been asked to reflect on the relation between my Christian faith and my vocation as a poet. Free to choose my texts, I had naturally gone for the opening verses of Genesis, on the one hand, and St John’s Gospel, on the other: those parallel and related accounts of creation in and through the Word.

“The heart of any poet”, I said, “would leap to find that in this mysterious account of God himself, and of his primal act of creation, the Word, the Logos or essence of all meaning, has a central place. For a poet, all words have a magical, generative power. They exist in themselves before the creation of a poem, and it is in, and through, and out of them that the poem comes into being.

“This opening passage of John’s Gospel offers us the transformative idea that we ourselves are a poem — that there is a poet behind the world, who not only speaks that world into being, but speaks us into it, so that we might behold its glory and respond with poems spoken back to the Maker.”

So far, so good; but then came my perilous illustration. I argued that scripture offered us a model of the cosmos, suggesting that the world was more like a poem than it was like a machine, and then I expatiated on the inadequacies of the “mechanistic model”: the idea that the world is simply a great piece of clockwork, unwinding independently of God, who is thus reduced to some distant, hypothetical, possibly blind watchmaker. “We invented clockwork”, I said, “and then made an idol of our own invention.”

It seemed to go down well, but, later, I had my come-uppance. By chance, or perhaps providence, I found myself seated in the combination room after dinner beside an eminent professor of mechanical engineering. He was witty, affable, enthusiastic, and excellent company, and he asked, at the end of the evening, with an air of innocence, whether any of us would like to ascend the clock tower in Great Court and see the beautiful inner workings of the clock itself, of which he had charge.

He gave us a marvellous tour, showing us the delicate, perfectly balanced, beautifully crafted mechanisms, opening the whole thing out as a work of art, which clearly gave him great joy. Then, he showed us the new experiments that his students had set up in the midst of the mechanism itself.

One experiment, with a laser trained on the great pendulum and linked to very fine measurements of the walls of the building, had shown that, on sunny days, tiny movements, caused by “the bimetallic effect” of one wall warmed by the sun and the other cooled in the shade, meant that the pendulum’s path curved infinitesimally, and, in those sunny hours, a “second” was slightly longer; and yet still the whole mechanism balanced and rebalanced, and never lost so much as a second in a month.

At no point did he ever allude to my sermon; but he left me in no doubt that, to the trained eye of an engineer, there is as much mystery and beauty in a mechanism as there is, to the trained eye of a poet, in a poem.