IELTS Academic Reading Practice Test 257

The Great Wall of China is not one structure but a family of walls, and the long, brick-faced ramparts that visitors know best are the work of one dynasty. Most of what survives today was built between 1368 and 1644, when China was ruled by the Ming. Earlier walls had been made largely of rammed earth, which crumbles over the centuries; the Ming faced theirs with stone and fired brick, and these materials have proved far more durable. According to a survey completed by China's heritage authorities in 2012, the Ming wall runs for some 8,800 kilometres.

Fortifications on China's northern frontier are much older than the Ming. During the Warring States period, before China was unified, rival kingdoms threw up earthen walls to protect their borders. After the first emperor, Qin Shi Huang, unified the country in 221 BCE, he is said to have joined several of these walls into a single line. The traditional account owes much to later writers, and archaeologists have found far less of his wall than legend suggests. The Han dynasty later extended fortifications westward, into what is now Gansu and Xinjiang, to protect the Silk Road trade.

The Ming did not at first rely on walls alone. Having driven the Mongol rulers of the Yuan dynasty out of China in 1368, the dynasty's founders preferred to attack their northern enemies in the field, and early Ming emperors led armies far into the steppe. Walls were repaired, but they were one instrument among several. The balance shifted in the fifteenth century, when Ming armies suffered serious defeats and the government adopted a defensive posture. From then on, fortification became the central element of frontier policy.

That policy's vulnerability became clear in 1550, when the Mongol leader Altan Khan led a great raid towards the capital. His forces defeated a Ming army in the field and plundered the outskirts of Beijing, and although they withdrew, the humiliation was considerable. The raid showed that a line of walls was only as strong as the troops who manned it and the command behind them. Such failures prompted the largest programme of wall building in Ming history.

The general most closely associated with this work is Qi Jiguang, who had made his name fighting pirates along the south-east coast. In 1569 he was transferred to the northern frontier, where he supervised the rebuilding of the wall between the capital and the sea. Qi's wall was taller and thicker than what had gone before, and it was studded with a new kind of structure: the hollow watchtower, large enough to shelter a garrison, store weapons and hold supplies. Hundreds of such towers were built along the sections he controlled.

Ming builders used whatever the landscape provided. In the mountains near Beijing they quarried limestone and granite, cut it into blocks and laid it with lime mortar; on the loess plains further west they continued the older technique of rammed earth, packing damp soil into wooden frames and pounding it solid. Bricks were used wherever they could be made in quantity, especially for parapets. Analysis of mortar from Ming walls has found that some of it was mixed with glutinous rice, a practice recorded in Chinese building manuals, and the starch appears to have made it stronger.

Daily life in a garrison was organised around signalling as much as fighting. Beacon towers stood within sight of one another, and guards who spotted an approaching force were expected to light a fire at night or raise smoke by day; the number of fires, or the colour of the smoke, could indicate how large the enemy force was. News could travel hundreds of kilometres in a few hours this way. Soldiers were also expected to grow much of their own food, and long stretches of wall were flanked by military farms.

Building and maintaining the wall consumed enormous resources. Stone had to be quarried and hauled up steep slopes, bricks fired in kilns, and pay and food carried to remote garrisons; the Ming state devoted a substantial share of its revenue to the frontier. Labour came from soldiers and from peasants conscripted for fixed periods, in harsh northern conditions. Historians have argued about the cost in human life, but the popular stories of workers buried within the wall rest on very little reliable evidence.

Yet the wall was never simply a barrier. Its gates were the points at which trade with the steppe was taxed and regulated, and the Ming state was as concerned with smuggling and unauthorised movement as with invasion. Merchants bringing horses, furs and salt crossed at designated passes, and the wall determined where they could do so. In this sense it worked less like a fence than like a customs house stretched across hundreds of kilometres, marking the edge of imperial authority.

In the end the wall did not save the dynasty. In 1644 the rebel Li Zicheng took Beijing, and the Ming general Wu Sangui, who commanded the pass at Shanhaiguan, opened the gate to Manchu armies from the north, who went on to found the Qing dynasty. The frontier that the Ming had fortified against the Mongols was finally breached from within. Later generations let the wall decay, and the belief, still often repeated, that it can be seen from the Moon with the naked eye has been disproved by astronauts.

Anyone who steps into the church of San Vitale in Ravenna, in northern Italy, confronts a surface that seems to have been made of light. The walls above the arches are covered with images of emperors, angels and saints, composed of thousands of tiny cubes of coloured stone and glass. Each cube, or tessera, is roughly square and only a few millimetres across, and the picture is assembled from them much as a photograph is built from pixels. Mosaics of this kind were made across the eastern Mediterranean between roughly the fourth and the fifteenth centuries; Ravenna, for a time the seat of imperial government in the west, preserves the finest surviving group.

Tesserae were cut from whatever material was available and suitable. Marble and limestone provided whites, greys and warm colours, while coloured glass, known as smalti, supplied the vivid blues, greens and reds that stone could not. Gold tesserae were made by a different method: a thin sheet of gold leaf was laid on a pane of glass and a second layer of glass was fused over it, so that the metal was sealed inside and could neither tarnish nor be rubbed away. Analyses of the glass have shown that much of it was not made for the purpose at all but was recycled from older Roman vessels and broken window panes, melted down and coloured again.

A mosaic was not applied to a bare wall. Builders first laid one or two rough coats of lime plaster to give a level surface, then a final, finer layer into which the tesserae were pressed while it was still soft. Only as much of this top layer was applied as the team could cover in a single day, because lime sets hard within hours; the joins between one day's work and the next can sometimes still be traced in a finished mosaic. Work normally began at the top of the wall and moved downwards, so that falling mortar would not spoil the areas already completed.

Designs were planned in advance. Craftsmen appear to have worked from pattern books and from schemes drawn on the plaster, rather than from full-size drawings of the kind later European painters used; because the surface was covered so quickly, few underdrawings survive. The size of the tesserae was varied deliberately: small cubes were used around faces and hands, where fine detail was needed, and larger ones in backgrounds and drapery, where they would be seen from far below. Setting the cubes at slightly different angles also changed the way light was reflected, so that a figure could appear to flicker as a lamp moved.

The mosaics of Ravenna raise a question that has never been settled. San Vitale was decorated in the 540s, shortly after the emperor Justinian's armies had taken the city from the Ostrogoths, and the panels showing Justinian and his wife Theodora are among the most famous images to survive from the ancient world. Some scholars have argued that craftsmen must have been brought from Constantinople, then the centre of the empire, because the technique is so accomplished. Others point to a strong local tradition and to differences of style, and maintain that the workshops were already in Ravenna. No document names the artists.

Mosaics were also vulnerable to theology. In 726 the Byzantine emperor Leo III began a policy of opposition to religious images, and in a second period, from 814 to 842, the making of such images was again forbidden. Figurative mosaics were destroyed or covered over, and crosses were set in their place. The great church of Hagia Sophia in Constantinople, built in the sixth century, seems to have been decorated originally with plain crosses, and its surviving figures of emperors, the Virgin and Christ belong to later centuries. The dispute ended in 843, when the veneration of images was restored.

For a long time the only way to study mosaic glass was to remove a piece and grind it up, which conservators were understandably reluctant to permit. Portable instruments have changed that. X-ray fluorescence can identify the elements in a tessera in a few seconds without touching it, and reflectance spectroscopy can distinguish types of glass by the way they reflect light. Such work has shown that workshops drew on several different supplies of glass, and that some panels were repaired with material from elsewhere. What these methods cannot do is establish when a mosaic was laid, since the composition of the glass says nothing about the date of setting.

Visitors should also remember that they are looking at objects that have been repaired. In the nineteenth century, when mosaics in Ravenna and elsewhere were cleaned and consolidated, damaged areas were sometimes filled with new tesserae and, in a few cases, whole sections were lifted and reset. Such interventions saved buildings that might otherwise have lost their decoration, but they make the task of distinguishing original work from later repair extremely difficult. Scholars now study the mortar as well as the cubes, since the lime bed underneath may preserve traces of the first setting.

None of this diminishes what survives. A mosaic is a record of materials, of labour and of belief at once, and its makers left no account of their intentions. What a visitor sees is the product of a workshop, of centuries of use, and of the decisions of those who restored it.

Every country keeps a calendar of remembrance, and no date on that calendar is neutral. A public holiday marks out a day on which citizens are invited to remember something together, whether a founding settlement, a military victory, a deliverance or a death. Some dates are chosen to celebrate a beginning, others to commemorate a loss. Because governments choose the dates and write the story, commemorative days have always been instruments of nation-building as well as occasions for reflection. In recent decades, however, several of these dates have been challenged, and the arguments now raised about them deserve more attention than they usually receive.

The case for revision begins with the obvious point that commemorative days were invented at particular moments for particular purposes. Columbus Day, for example, was promoted in the United States partly by Italian-American organisations seeking recognition, and it became a federal holiday in 1937; the story it told of a single voyager discovering a continent now seems to many people both inaccurate and insulting to the peoples who were already there. Some cities and states have replaced it with a day honouring indigenous peoples. When a holiday's founding story no longer matches what a society believes about itself, the argument runs, the holiday should give way.

The opposing case rests on the value of continuity. A calendar is one of the few things a divided society holds in common; if every generation rewrites it, the shared element disappears and each group retreats to its own observances. Rituals also work through repetition: a day observed every year for a century acquires a meaning that a newly invented one cannot have. Critics of change add that symbolic revision is cheap, and that renaming a day allows a government to appear progressive while doing nothing about the disadvantages that the original holiday obscured.

I have some sympathy with both positions, but I think the debate is confused by a failure to distinguish between two kinds of commemoration. A holiday that celebrates a person or an achievement makes a claim that can be examined and, if necessary, rejected. A holiday that marks a shared experience of loss, such as the armistice that ended the fighting in 1918, makes a different kind of claim, and one that is much harder to revise without doing harm. The first kind can reasonably be altered when the historical judgement behind it changes; the second should usually be kept, and if anything widened.

The history of Armistice Day shows how a commemoration can change without being abandoned. The day was instituted to mark the silencing of the guns on 11 November 1918 and was observed with a two-minute silence and, in Britain, with poppies sold to raise money for wounded servicemen. As the generation that fought the First World War died, the day was extended to honour those lost in later conflicts and, in some countries, to include civilians and victims of terrorism. Few people regard this widening as a betrayal of the original purpose; it is widely seen as a natural development.

New commemorations can also become traditions within a single generation. Martin Luther King Jr Day was signed into law in the United States in 1983, after years of campaigning, and was first observed in 1986. At the time it was opposed by senators who questioned King's politics, and some states resisted the name, a few combining it with a holiday honouring a Confederate general. Within two decades the day had become an ordinary part of the American year, marked by volunteering and school assemblies. What was once controversial now feels permanent.

Yet the sceptics are right about one thing. Changing a name on a calendar is easy; changing the conditions in which people live is not. A city that renames a street after a minority leader while its schools remain segregated has achieved very little. Symbolic acts are not therefore worthless — what a society chooses to honour shapes how its children understand who belongs — but they should be judged by whether they lead anywhere. The point is not that symbols are trivial, but that they are not enough on their own.

Some disputes cannot be resolved by rewriting a story, because they concern a date itself. Australia Day falls on 26 January, the anniversary of the arrival of the First Fleet at Sydney Cove in 1788, and for many Aboriginal Australians it marks the beginning of dispossession; some call it Invasion Day and campaign for a different date. Those who defend 26 January argue that a national day must be one that everyone can share. A date chosen long ago was chosen by particular people for particular reasons, and those reasons can be examined. The choice of date cannot be settled by historical accuracy alone, because the disagreement is about what the nation is, not about what happened in 1788.

My own view is that commemorative days should indeed change, but slowly and for reasons that are stated publicly. The test is not whether a holiday makes anyone uncomfortable, nor whether it has survived for a long time, but whether altering it would help a society to understand its past more accurately and to live together more decently. On that test, some changes are clearly overdue; others, advanced mainly to attract attention, are best resisted. A calendar is a statement about what matters, and statements can be corrected.