Something unusual has happened at Henry Moore's 50-acre estate in rural Hertfordshire. For the first time ever, another sculptor, a Frenchman called Auguste Rodin, that great, 19th-century embodiment of the Hellenic tradition, has moved in to challenge the right of Moore's own sculptures (which range from figure groups to more abstract forms) to rule over these gently undulating fields. Today, at Eastertide, these are populated by troubled lambs skittering here and there in pursuit of their mothers. And what is the outcome of this challenge? Moore comes out seeming grave, slow and ponderously monumental, and Rodin, who was born more than 50 years before him, spirited and much lighter on his feet.
They sit quite close to each other, out in the swing of the blustery landscape, the Moores and the Rodins, eyeing each other suspiciously, wondering whether they share any common values. In 1917, the year of Rodin's death, Moore was serving in the Civil Service Rifles, 15th London Regiment. He fought in the Battle of Cambrai, and was invalided out after a gas attack. Within three years, he was studying sculpture at London's Royal College of Art.
To the young sculptor of those early decades of the 20th century, Rodin would have seemed a little like yesterday's man. Moore's passion was for everything that had happened before the Greeks made their mark, older and more primitive traditions of the kind that he saw represented in the great collections at the British Museum – Cycladic, Oceanic, African art. As he matured, Rodin came to mean more to him. He became increasingly engrossed in how Rodin worked: the way he combined parts of the body; how he seemed to profit by chance; how he succeeded in giving vigour and animation to a three-dimensional object. Fundamentally, they were both in pursuit of an answer to the same question: how to make an object work in the round. And yet when you stride between them, mud greedily sucking at your boots all the way, it is still the differences that make the greater impact. Moore is constantly striving to give heft, weight, gravity, some kind of immemorial pomp, to the overall form of a piece, whether it be a reclining nude that seems to modulate into the heave and ruck of landscape or a more abstract form that grows from its columnar plinth. With Moore, the devil is not so much in the detail. Our eye glides smoothly across, through and round a Moore. Rodin is quite different. His sculpture has much more bite.
We snag on every bit of a Rodin. One reason for this is quite simple. Rodin was a modeller – he manipulated clay with his fingers, messing with the stuff – whereas Moore was a carver. Even a cheese-grater was good for a bit of frottage. With Moore, you see the smoothly flowing lines; with Rodin you are caught short by jaggedness, pernicketyness, the ceaseless fuss of detailing.
The single greatest surprise here is to see Monument to the Burghers of Calais, which usually sits on its low plinth in Victoria Tower Gardens in the shadow of Parliament, out here in the fields. In this unaccustomed location, this multiple figure group looks more restlessly engaging than ever. Its closeness to the ground alarms us. Should a sculpture be eyeballing us to this extent? The way that the five burghers work in relation to each other never ceases to fascinate. They come at us from all directions – everywhere we stand gives us a slightly different take on the drama of the piece.
At a certain stage in the planning, Rodin visualised the group processing in a line. Now they seem to exist in a febrile, huddling swarm of collective anguish, not knowing in quite which direction to turn. The great key to the City of Calais itself hangs limply from a hand at the back – you only see it when you walk behind the sculpture – as if it is the most inconsequential of matters.
Rodin called this piece his novel, and you do indeed experience the possibility of multiple narratives opening up to you as you circle and circle it, staring up into each face, observing each writhing finger. If you view it from the front, you will see, on the extreme right, the clothed figure of Jean d'Aire.
Just a couple of hundred yards away, standing on its own in a handsome triangular field, stands Jean d'Aire yet again, but this time he is in the form of a monumental nude. Every muscle of his body seems taut and pent. His fists are clenched. The energy of the figure positively crackles.
A little way down the same field stolidly hunches a Moore sculpture called The Arch. It belongs to landscape – you could call it a kind of bony extension of landscape (as Moore's figures and groups often strove to be) – but it also looks and feels lumbering and strangely inert. Is it a problem of scale? Is it too big for its own good?
Moore's growing fascination with Rodin extended as far collecting works by the master. Deep into a field beside the Exhibition Gallery, which houses drawings, smaller sculptures and, on an upper floor, a selection of works collected by the two men during their lifetimes chosen by Moore's daughter Mary, you spot a tall, lonely column – about three metres in height – capped by a kind of hybridised Corinthian capital. On the top of that capital, on a plinth that just overflows beyond its limits, strides Rodin's tiny, headless, armless Walking Man, a cast of which Moore owned, striding today against a sullen skyline.
Moore, we know, interrogated this piece, ceaselessly, for clues to its success. How had Rodin managed to inject it with such ceaseless vitality? How had he managed to give the impression that the figure's weight appears to shift backwards and forwards, depending upon your angle of view? How, above all, had he managed to achieve such an illusion of springy movement? He pondered on the way in which the left leg seemed to drag. He photographed the work, again and again, for clues to its success – some of those dramatically engaging photographs can be seen on the walls of the upstairs gallery.
And yet, as we are aware, Moore was not after an illusion of movement. As far as he was concerned, it was not a sculpture's job, in the middle of the 20th century, to pretend that the body was in motion. Rodin may have been admirable, even magnificently informative in his way, but he was an heir to that muscleman Michelangelo, and Moore was facing in a slightly different direction.
The question that remains though is this: does all this stolid monumentality give his sculptures enough life in other meaningful ways? From the evidence of this show, the answer must be sometimes yes but often no. Moore too often seems leaden and dull and endlessly self-recapitulating.
Only one of the outdoor sculptures by Moore in this open-air tussle of the Titans seems to be an unqualified success, and that is the largest. It is called Large Figure in a Shelter, and consists of two huge cup-like arms, looming concavities, enclosing a figure that seems to embody fear and frailty. Immediately, we think back to Moore's greatest achievements, his drawings of victims of the Blitz huddling for shelter in the London Underground, a selection of which can be seen in the indoors gallery here. They are so haunting, so monumentally classicising, the figures in these dark drawings. Yes, those pesky Greeks, in the end, fed him his finest hand.
Moore Rodin, The Henry Moore Foundation, Perry Green, Much Hadham, Hertfordshire (01279 843333; henry-moore.org) to 27 October