Â鶹ԼÅÄ

Double-headed serpent (made between 1400 and 1700). Mosaic; from Mexico

Listening to the sounds of buskers in the heart of Mexico City today, beating Aztec-style drums and wearing feathers and body paint, [I know that] these buskers are not just trying to entertain passers-by, they're trying to keep alive the memory of the lost Aztec Empire, that powerful, highly structured state that dominated Central America in the fifteenth century, and which was destroyed by the Spanish conquistadors, led by Hernán Cortés, around 1520. The buskers would have us believe, and you can believe it if you like, that they are the heirs of Moctezuma II, the emperor whose realm was brutally overthrown by the Spaniards in the Great Conquest of 1521.

In the course of the Spanish Conquest, Aztec culture was almost completely obliterated. So how much do we, can we, actually know about the Aztecs that these buskers are honouring? Virtually all the accounts of the Aztec Empire were written by the Spaniards who overthrew it, and so they have to be read with considerable scepticism. It's all the more important, then, to be able to examine what we can consider as the unadulterated Aztec sources, the things made by them that have survived. These are the documents of this defeated people, and through them, I think, we can hear the vanquished speak.

"When you look at these objects in the gallery, the workmanship is extraordinary. But that awe is just taken to another level when you look at them in high magnification, because you can see not just the consummate skill of whomever it was that produced these things, but the hours and hours of time that must have gone into their production." (Rebecca Stacey)

"The two heads in this snake is the symbol of dualism, which was a fundamental part of the Aztec religion. All the deities have a dual nature - male, female, birth, death, night, day, generation and destruction." (Adriane Diaz Enciso)

This week I'm looking at objects that take us into the sixteenth and seventeenth centuries, when western Europeans sailed off to explore, and in some cases conquer, the world. Today, I'm not on ship with the conquerors, but ashore with the defeated . . . I'm with the Aztecs.

At the beginning of the sixteenth century, the Aztecs had of course no idea that they were on the brink of destruction. They were a young and vigorous empire, triumphantly in possession of territory that ran from Texas in the north to Guatemala in the south, and included the great bulk of modern Mexico. They had a flourishing culture that produced elaborate works of art which were more precious to them than gold - turquoise mosaics.

When these Aztec mosaics were first brought to Europe by the Spanish in the 1520s, they caused an enormous stir. This was the first glimpse of a great civilisation in the Americas, completely unknown to Europeans, and evidently every bit as sophisticated and luxurious as their own. The double-headed serpent is one of the most highly crafted and strangely compelling of these rare Aztec survivals.

The serpent is made up of about two thousand tiny pieces of turquoise, set on to a curved wooden frame, about a foot and a half (45 cm) wide. The snake's in profile. It's got one body, shared by two heads, and the body curls up and down in a 'W' shape, to finish at each end in a savage, snarling, head. The body of the snake's entirely in turquoise, but when you come to the snouts and the gums, a brilliant red shell has been used, and then the teeth are picked out in white shell, culminating in huge, terrifying fangs.

As you move up and down in front of the case, and let the light play over the turquoise pieces, the changing colours seem to live, and the pieces look not so much like scales on a snake but feathers shimmering in the sunlight. It's an object which is at once both snake and bird. It's mysterious, it's disturbing, it's a work of high art, and a vehicle of primal power. You know that you are in the presence of magic.

The way that the serpent was made gives us a lot of useful information. In the British Museum's Conservation Department, Rebecca Stacey has been examining the materials that make up the object as well as the resins or glue that hold the two thousand-odd pieces together:

"We have done a range of analyses, we've looked at the variety of different shells that are present. The bright red shell used on the mouth and the nose is from the 'Spondylus princeps', the thorny oyster, which was a really highly prized shell in ancient Mexico because of this fabulous scarlet red colour, and also because it involved diving to great depths - dangerous deep-sea diving - to harvest it as well. Even the adhesives, which are plant resins, were important ritual materials, because they are the very same materials that were used as incense and as ritual offerings. They had a very important ceremonial life of their own. A number of different plant resins were used: pine resin, fairly familiar, and also tropical bursera resin, which is a much more aromatic resin, very much associated with incense, and still used as incense in Mexico today."

So the different elements of this magical object are held together - almost literally - by the glue of faith. Rebecca, and scientists across the world, have established that turquoise in Aztec Mexico was transported over huge distances. Some pieces were mined over a thousand miles (1,600 km) from the capital, Tenochtitlan, now Mexico City. Goods like turquoise, shells, and resin, were traded across the whole of Central America, but it's more likely that the components of our serpent were forcibly exacted as tribute - compulsory levies from the peoples whom the Aztecs had conquered. This empire had been created only in the 1430s, less than a century before the Spaniards arrived, and it was maintained by aggressive military power, and tribute of gold, slaves and turquoise, sent regularly - and reluctantly - to Tenochtitlan by the subject provinces. Turquoise was highly prized, and it was the focus of great rituals, designed to impress and to intimidate - part of that "shock and awe" that keeps imperial administrations in place. We know about this through the writings of Diego Duran, a Dominican friar who was extremely sympathetic to the Aztecs, learning their language and transmitting their culture and their history. So although he's Spanish, we can probably rely on his account of a tribute ceremony:

"People attended with their tribute of gold, jewels, finery, feathers and precious stones, all of the highest value and in great quantities . . . so many riches that they could not be counted or valued. All of this was done to show off magnificence and lordship in front of their enemies, guests and strangers, and to instil fear and dread."

The wealth generated by this trade and tribute allowed the Aztecs to build roads and causeways, canals and aqueducts, as well as major cities - urban landscapes that astonished the Spaniards as they marched in amazement through the Empire:

"During the morning, we arrived at a broad causeway and continued our march. And when we saw so many cities and villages built in the water, and other great towns on dry land, we were amazed, and said that it was like the enchantments they tell of in the legends of Amadis, on account of the great towers and buildings rising from the water, and all built of masonry. And some of our soldiers even asked whether the things that we saw were not a dream."

Turquoise was also a key element in the regalia of the Aztec ruler Moctezuma II, who conducted great rites of human sacrifice wearing a turquoise diadem, turquoise nose-plug, and a loin-cloth with turquoise beads. The two-headed serpent was almost certainly worn or carried in such a religious ceremony, perhaps even at Moctezuma's accession to the throne. It would have had tremendous symbolic value, not only because of its precious turquoise, but also because it's fashioned as a fabulous snake. The poet and writer Adriana Diaz Enciso explains the snake's connection to the Aztec gods, and especially to the great feathered serpent god, Quetzalcoatl:

"The snake was important for the Aztecs as a symbolism of regeneration and resurrection. In the temple of Quetzalcoatl in Tenochtitlan you can see some sculptural reliefs of snakes that are pouring water out of their mouth, and the water is falling on the crops to help them grow. So it has that meaning of fertility. The figure of Quetzalcoatl is seen in several sculptures and drawings as a snake with a body covered with feathers. The fusion of this bird, the quetzal, and the snake, which is a symbol of the earth, is the fusion of the powers of the heaven and the powers of the earth so, in that sense, it's also a symbol of eternity and of renewal."

And when we go back to the double-headed snake, it becomes clear that the tiny, carefully-angled, turquoise pieces are not far off the colour of the blue-green tail-feathers of the quetzal bird, and they've been cut and bevelled to shimmer and flash just like the quetzal's iridescent feathers. This double-headed serpent may in fact be a representation of the god Quetzalcoatl and, if so, that would link it directly to the momentous events surrounding Hernán Cortés's arrival in Mexico.

Spanish accounts at the time recorded the encounter between Cortés and Moctezuma. They state that Moctezuma saw Cortés as an incarnation of the god Quetzalcoatl. Aztec legend had told that Quetzalcoatl floated out into the Atlantic, and would one day return as a bearded and fair-skinned man. And so, the Spanish writers tell us, instead of summoning his troops and fighting, Moctezuma presented Cortés with the homage and the exotic gifts fit for a god. One of these gifts is reported to have been "a serpent wand inlaid with turquoise". It might even have been this double-headed serpent.

We shall never know the full truth, but we do know that the Aztec tribute system was fiercely resented, and led many of the subject peoples to join the Spanish invader. Without the support of these disaffected local armies, the Spanish would never have been able to conquer Mexico. Appropriately, the double-headed serpent tells both the stories. It is a document of the Aztec Empire at the height of its artistic, religious and political power. It's also evidence of the systematic oppression of its subject peoples, that ultimately destroyed it. Soon Moctezuma was dead; Tenochtitlan was reduced by the Spaniards to smoking rubble, and with no emperor and no capital, the Aztec Empire was effectively destroyed. These catastrophes were swiftly followed by the impact of devastating European diseases, especially smallpox. It's been suggested that as much as 90 per cent of the local population died within a couple of decades of the arrival of the Spaniards.

In the next programme we have not a serpent made of turquoise, but a pair of porcelain elephants from Japan . . . and these tell a very different story about war and art.