It's a three-body problem. How the mutual gravitational interaction of three masses – familiarly the Moon and the Earth and the Sun – leads to stable orbits exercised Sir Isaac Newton and his contemporaries. It's not a trivial problem even now, admitting to no trivial or general solution, and it's the inspiration behind a play that examines closely the conflict within one of the greatest scientific intellects of all time, Sir Isaac Newton.

Written by Craig Baxter and directed by Patrick Morris, Let Newton Be starts, appropriately enough, with the young Newton: a sickly, tiny child not expected to survive until the next Spring. Against the odds, the young Isaac survives, although being fit for naught else is packed off to university – Trinity College, Cambridge. It is here he comes into his own, moving steadily through the ranks, from Fellow to Member of Parliament to President of the (yet young) Royal Society.

The three-body problem ties the play together. There are three actors, playing Newton as boy, as young man, and as scientific patriarch. All the Newtons struggle with the doctrine of the Trinity – one God, Three persons – yet, asks Newton, how can the One God revealed in Scripture ever be split between three different beings? The Newton of Trinity College, lecturing mathematics to the few students that attend (and fewer that understand) is challenged by his younger self to return to the vigour and dogma of youth, to take Holy Orders as required by the University, to give himself up to the pure pursuit of God. In desperation and conflict, Newton lectures to the walls.

He experiments on himself. In one remarkable scene, the Newton of Trinity College peers at the sun, his fingers keeping his eyelids apart – while the elder and younger Newtons on stage help him count the seconds. Then he pokes a bodkin into the corner of his eye and records the colours and shapes he sees. A few days' rest in a darkened room, and he repeats the experiment.

Although there are only the three actors, they occasionally play other roles. Edmund Halley visits the elder Newton, asking him what curve would best describe the path of the planets, given the force of attraction towards the Sun to be reciprocal to the square of the distance.

"An ellipse," Newton replies, impatiently.

Halley asks him how he knows – and Newton says he is too busy, too busy as he scribbles yet more equations. "How do you know?" Halley persists, until, finally,

"I calculated it!" Newton snaps, as if anybody worthy of Newton's friendship should have grasped it intuitively.

Not being able to find the equation in his notes, Newton promises to write to Halley. He does so, eventually – the letter becoming the Principia: Newton's greatest and most celebrated work.

Throughout the play, Newton struggles with his duty to God versus following his scientific calling. There is a resolution of sorts: studying the natural world and working out the laws of gravity (and there is, for this reviewer, a moment where the formula F=ma and the laws of gravity suddenly make fleeting intuitive sense of why planets and suns fall towards each other yet do not collide, perhaps in the way that Newton operated all the time).

And we see other sides of the Newtons: the penitent who makes a list of his sins (all the while encouraged and condemned by the younger Newton); the distaste of the younger and the older at the student throwing up (losing at cards a minor crime); the alchemist, strange to modern audiences but very much a part of his genius; the relief at dispensation to dodge holy orders from Charles II; the experiments with prisms and chemicals and telescopes – and above all these there is the sense that somehow, somewhere, the three Newtons are merely rediscovering the thoughts of the incalculable God, the great I AM who set everything in motion in the first place.

Finally, Newton disputes with Leibniz over who invented calculus (what Newton termed his 'method of fluxions'). The argument, with a suitably ludicrous, faux-German Leibniz speaking from the audience, morphs into a theological discussion – is it a clockwork universe? How does God act to keep everything running? – and goes initially in favour of Leibniz until, aided by the young Isaac, the elder Newton skewers him on a point of logic. There is no reply from Leibniz, as – in a scene tragically comic – he has died.

The play’s dialogue is taken exclusively from the recorded words of Newton and his contemporaries. He is not merely the great scientist, nor is he standing on the shoulder of giants. He is a boy, a man; conflicted yet arrogant; sensitive yet crass. In the end, Newton is.

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Let Newton Be! is currently touring the UK and will move to North America on the 13th of April.