A wild figure twists in the deep blue darkness of the opening gallery, his naked body convulsed. Spotlights catch the gold in his eyes. His hair is a tangle of metal-bright whorls, his beautiful head is thrown back in pain or ecstasy – or possibly both, for one leg flails behind him and exhaustion is setting in. He might be dancing, but he could also be dying.
This lifesize sculpture was discovered off the coast of Sicily only a few years ago. Fishermen dragging the deep waters of the Straits felt the heavy burden in their nets. You can imagine the shock of it, the bronze figure rising out of the waves, dripping and gleaming in the sunlight for the first time in centuries or maybe more. For this satyr was made in ancient Greece, probably in the fourth century BC, and perhaps even by the renowned sculptor Praxiteles. Who knows when it was lost?
It is a shattering sight, this brilliant figure emerging out of the blue at the start of the Royal Academy show and it sets the whole tenor of the exhibition. For Bronze is all about amazement. It brings together more than 150 bronze sculptures from across the world, spanning continents and several millennia, each made for different purposes and each bewitching in quite distinct ways, and pitches them all together.
There are no angles, no theories, no revisionist arguments or scholarly axes to be ground. There is no chronology. Visitors are not even waylaid with the laborious technicalities of each piece as the various processes of sculpting in bronze are superbly explained in a single step-by-step gallery.
The exhibition is entirely given over to wonder and it is all the more wonderful for it.
Bronze is an alloy of copper with lesser amounts of tin, zinc or lead. It is so tough, resistant and outstandingly strong that it can survive bomb-blasts, earthquakes, the weapons of war and the ocean's erosions without cracking or wearing away. It is so ductile that artists can use it to defy gravity with flights of fantasy, such as Giambologna's leaping Mercury or Barthelemy Prieur's fabulous Acrobat Performing a Handstand, a feat that could not be achieved in clay or marble.
And it is so malleable that it can be twisted into corkscrew curls that look like bright metal shavings – witness the fabulous coiffure of a female head found on a herm post in Herculaneum – or beaten to parchment fineness. Among the most celebrated objects in the show is the Chariot of the Sun, dug out of a Danish peat bog in 1902, which takes the form of a horse on four elegant wheels pulling a disc of ethereal delicacy and brightness.
One side represents the sun in splendour, the other is sunless, so that perhaps the chariot was made to be wheeled out and back at the beginning and end of the day in some mysterious ritual. Made more than 3,000 years ago, it is a work of unparalleled sophistication, in so many senses drawn out of darkness.
Bronze can be cast on a staggering scale. A colossal figure of Lucius Mammius Maximus (its inscriptions, incidentally, giving us some idea of when this benefactor lived) stands almost three metres high on its pedestal. With its torrential drapes, like rivulets of hardened lava, it is as intimidating now as it may have been to the citizens of Herculaneum above whom it towered.
And on the tiniest scale, bronze can be as intimate as a whisper. Donatello's tiny cherub fairly bursting with mirth as he shakes a tambourine has more eloquence in its single upcurled toe than in all the muckle monuments of Rodin.
Rodin is here, of course, along with other familiar bronze-casters. Germaine Richier's praying mantis is half-human, half-critter, lurking opposite one of Louise Bourgeois's outsize spiders hanging halfway up a wall. Picasso's Baboon and Young is a classic metamorphosis of bric-a-brac into magic, fusing toy cars, jug handles and the innards of an old automobile into a monkey-world variation on the old theme of Madonna and child.
Indeed, some extremely famous works have travelled to London for this show, including The Chimaera of Arezzo, a mythical fire-breathing hybrid of lion, goat and serpent that is regarded as the masterpiece of Etruscan casting. Lost before the birth of Christ, it was found again in 1553 and restored by Benvenuto Cellini himself.
You would have to travel to Italy to see this fierce creature ordinarily, just as you would need to visit Bulgaria to witness the staggering realism achieved by the anonymous sculptor of the Thracian King Seuthes III. With its throbbing vein in one temple, its tense frown and blazing eyes – the whites in alabaster, the eyelashes of copper and the irises now oxidised to green – this head has real force of personality: a sensational feat of polychrome portraiture.
Bronze carries its age so beautifully in the marvellous range of blue-greens through which it turns, like the seasons. It also responds like no other sculptural material to different finishes – matt, chafed, patinated, incised – and to the fall of light on its surfaces.
It can gleam or glower, appear bright as a mirror in the case of a semi-abstract Brancusi bird, or rough and grey as old clinker in the hands of Giacometti.
Passers-by can change it, too, with their touch. Here is the tomb of a Florentine monk, a portrait softened by centuries of feet walking across it on their way to the altar. And here is a Renaissance bronze of a gigantic wild boar, its snout brightened by centuries of petting.
Who would think that human beings could create such an extraordinary variety of forms of this precious stuff, from gods to gross beasts? That may be the show's greatest revelation. The Egyptians deify domestic cats with the aid of bronze. The Greeks fix the motion of athletes to perfection. The Romans make lasting monuments.
And the American sculptor David Smith (if only we had more of his work in Britain) makes jokes. His humorous Portrait of a Painter, fashioned out of an easel topped with a palette, its thumb-hole an eye, sends up the painter's pomposity – I Am My Art – by casting the assembly in age-old bronze.
David Ekserdjian and his curatorial colleagues have arranged this show with such freedom and flair that each work makes the next look more exceptional by contrast. The galleries may be grouped by subject – humans, animals, objects, gods – but the exhibits are placed in the most unexpected conversations. In one room, you might have a fierce Chinese yogi, an ultra-refined Benin head from Nigeria and a doleful Renaissance saint all sculpted around the same period, just to show you what mankind could make of itself, and its precious metals, across different continents.
Bronze feels like the British Museum condensed to an ideal size. It centres on a single substance, and everything that can be done with it, but mainly as a way of considering the essence of sculpture by other means. It is dazzling, eccentric and surprising in its every shining object from first to last.
