IELTS Academic Reading Practice Test 47

For most of history, money meant metal. Coins of gold, silver, copper or bronze carried value in themselves, because the metal they contained could be melted down and sold. Paper money is different in kind. A banknote is worth almost nothing as a material object; its value rests entirely on the confidence of its users that someone, whether a merchant, a bank or a government, will honour the promise it represents. How societies came to accept such promises instead of metal is a remarkable story, and it began not in Europe but in China.

Under the Tang dynasty, in the ninth century, merchants trading between the provinces and the capital faced the problem of carrying large quantities of copper coins over long distances. A system developed in which a trader could deposit coins in the capital and receive a certificate that could be exchanged for coins in another region. These certificates became known as flying money, because they allowed value to travel without the weight. They were not, however, true currency, since they were not passed from hand to hand in ordinary buying and selling.

The decisive step came in the province of Sichuan in the early eleventh century, during the Song dynasty. Sichuan used coins made of iron rather than copper, and since iron was worth comparatively little, even modest purchases required heavy loads of coins. Merchant houses in the provincial capital, Chengdu, began accepting deposits of iron coins and issuing paper receipts, known as jiaozi, which circulated in place of the coins themselves. The arrangement worked well until some of the issuers were unable to redeem their notes, causing losses and disputes. The state responded by taking control: an official office was established in the early 1020s, and the first government-issued jiaozi appeared in 1024. This is generally regarded as the earliest paper money issued by any government.

The Chinese experience also revealed a danger that would accompany paper money throughout its history. Because notes cost almost nothing to produce, rulers under financial pressure, especially in wartime, were tempted to print more of them than the economy could absorb. Under the Song, and later under the Mongol rulers of the Yuan dynasty, repeated over-issue led to falling values and rising prices.

The Venetian traveller Marco Polo, who described the court of Kublai Khan in the late thirteenth century, expressed astonishment that the emperor's subjects accepted pieces of paper made from the bark of mulberry trees in exchange for goods of real value. The Ming dynasty, which followed the Yuan, also issued notes, but these lost so much value that during the fifteenth century they fell out of use, and silver became the main medium of exchange.

Europe adopted paper money more than six centuries after China. In Sweden, part of the currency consisted of large copper plates, some of which weighed more than twenty kilograms. In 1661 a private bank in the capital, Stockholms Banco, founded by Johan Palmstruch, began issuing printed notes that could be exchanged for coins on demand, and these are usually described as the first banknotes in Europe. The notes proved popular, but the bank issued far more of them than it could redeem, and within a few years it had collapsed. Its failure led the Swedish parliament to establish a new bank in 1668, the institution that became the Riksbank, today the oldest central bank still in operation.

Across the Atlantic, paper currency emerged from military necessity. In 1685 Jacques de Meulles, the senior French administrator in the colony of New France, found himself without enough coin to pay the soldiers stationed there. His solution was to cut up playing cards, write a value on each piece and sign it, promising that the cards would be redeemed once money arrived from France. Five years later, the English colony of Massachusetts Bay faced a similar crisis when troops returned unpaid from a failed expedition against Quebec. The colonial government issued paper bills of credit to pay them, an issue often cited as one of the earliest examples of government paper money in the Western world.

The Bank of England was founded in 1694 to raise money for King William III's war against France, and it began issuing notes almost immediately in exchange for deposits. The earliest were written out by the bank's cashiers, each for the precise sum deposited, and were signed individually. From 1725 notes were partly printed, with the remaining details added by pen, and the first fully printed notes appeared only in 1855. During the nineteenth and early twentieth centuries, banknotes in many countries could be exchanged for a fixed quantity of gold, an arrangement known as the gold standard. Britain abandoned it in 1931, and in 1971 the United States stopped converting dollars into gold for foreign governments, severing the last formal link between the major currencies and precious metal.

The material of money has continued to change. In 1988 Australia issued the world's first banknote printed on polymer, a type of plastic, to mark the two hundredth anniversary of European settlement. Polymer notes last considerably longer than paper ones and can include transparent windows that are extremely difficult to counterfeit. Dozens of countries have since followed, including the United Kingdom, where the Bank of England introduced a polymer five-pound note in 2016. Yet the essential principle remains the one first tested in Sichuan a thousand years ago: a currency is only as good as the trust placed in those who issue it.

Lichens are among the most widespread organisms on Earth, yet they are also among the most overlooked. They form crusty patches on rocks and gravestones, leafy growths on tree trunks and shrubby tufts on the ground, and they occur from the polar regions to hot deserts and from the seashore to high mountain summits. Around 20,000 species have been described. Because they are often green or grey and grow in the same places as mosses, they are frequently mistaken for plants. In fact, a lichen is not a single organism at all, but a partnership between very different forms of life.

The composite nature of lichens was proposed in 1867 by the Swiss botanist Simon Schwendener, who argued that each lichen consisted of a fungus living together with an alga. The idea was greeted with hostility by many leading lichen specialists, who had spent their careers classifying lichens as independent organisms. Part of the difficulty was conceptual: biologists at the time were accustomed to thinking of each living thing as a separate, self-contained unit. Schwendener himself described the relationship in rather negative terms, believing that the fungus exploited the alga much as a master exploits a slave. Over the following decades, however, the evidence for his dual hypothesis became overwhelming, and lichens became a textbook example of symbiosis, a close and lasting association between different species.

In most lichens the fungus makes up the bulk of the body, or thallus, and determines its shape. Its threads form a tough outer layer and an inner network in which the photosynthetic partner lives. This partner is usually a green alga, though in a minority of species it is a cyanobacterium, and some lichens contain both. The photosynthetic partner uses sunlight to produce sugars, a substantial proportion of which pass to the fungus. In return, the fungus provides shelter from intense light and drying, and absorbs water and minerals from rain, dust and the surface beneath it. Cyanobacteria can also capture nitrogen from the air, which allows lichens containing them to grow on surfaces that are extremely poor in nutrients.

Recent research suggests that even this picture may be incomplete. In 2016 a team led by Toby Spribille published a study in the journal Science that examined two closely related lichens from western North America: one yellow and toxic, the other brown and traditionally eaten by some indigenous peoples. Puzzled that the main fungal partners of the two appeared almost genetically identical, the researchers searched for other organisms and found a previously unrecognised yeast, a different kind of fungus, embedded in the outer layer of the lichens. The yeast was far more abundant in the toxic species, and related yeasts were then detected in lichens from six continents. Whether these yeasts are genuine partners or simply common residents is still debated, but the discovery has encouraged scientists to view lichens as small communities rather than simple pairs.

Lichens are celebrated for their ability to endure conditions that would kill most other organisms. Many species can lose almost all of their water and remain dormant for long periods, then resume photosynthesis soon after being moistened. This tolerance of drying allows them to colonise bare rock, where there is no soil to hold water. In 2005 the European Space Agency tested the limits of this resilience by sending samples of two lichen species into orbit on a Russian satellite. For about two weeks they were exposed directly to the vacuum, extreme temperatures and intense ultraviolet radiation of space. When they were returned to Earth and examined, their capacity for photosynthesis had recovered almost completely.

The price of such toughness is extremely slow growth. Some crust-forming lichens on rock expand by only a fraction of a millimetre each year, and individual specimens in harsh environments are thought to be many centuries old. Scientists have turned this slowness to practical use. Lichenometry, a technique developed in the mid-twentieth century, estimates how long a rock surface has been exposed by measuring the diameter of the largest lichens growing on it, with growth rates calibrated against surfaces of known age, such as dated gravestones. The method has been applied to glacial deposits and rockfalls, although its accuracy is limited because growth rates vary with climate and local conditions.

Lichens are also highly sensitive to air pollution, because they have no roots or waxy covering and absorb water and dissolved substances directly from rain and the atmosphere. In the 1860s the Finnish botanist William Nylander, who lived in Paris, observed that lichens were disappearing from the city's streets while surviving in its parks, and he suggested that they could serve as indicators of air quality. By the 1890s, he reported, they had vanished even from the Luxembourg Gardens. Sulphur dioxide from burning coal was later identified as a major cause of such losses. Today lichen surveys are widely used to monitor pollution, and in several European cities the return of sensitive species has provided visible evidence that cleaner air has been achieved.

Lichens also matter to people and animals in more direct ways. In the Arctic, reindeer and caribou depend heavily on lichens for food in winter, digging through snow to reach them. Some species yield dyes that were once widely used to colour wool, and litmus, which shows whether a solution is acidic or alkaline, is extracted from certain lichens. Many lichens also produce unusual chemical compounds, some with antibiotic properties, which researchers are investigating for possible medical uses.

Every few years a commentator declares that the public library has had its day. Why, the argument runs, should taxpayers fund buildings full of printed books when almost any text can be downloaded in seconds and a search engine answers questions faster than any librarian? The argument has a superficial logic, and it has been influential: in Great Britain, according to figures compiled by the accountancy body CIPFA, almost 800 libraries closed between 2010 and 2019, as local authorities facing severe budget cuts looked for savings. I believe, however, that the case against libraries rests on a misunderstanding of what they have always been for.

It is worth remembering that the public library was never simply a warehouse for books. Between 1883 and 1929 the Scottish-American industrialist Andrew Carnegie paid for the construction of more than 2,500 library buildings, the majority of them in the United States, on condition that local communities provided the land and funded the running costs. Carnegie, who as a poor young immigrant had educated himself partly by borrowing books, saw libraries as ladders by which ambitious people without money could improve themselves. The books were the means; the purpose was opportunity. That purpose has not disappeared simply because the means have multiplied.

Indeed, the digital revolution has in some respects made libraries more necessary, not less. A significant minority of people still lack reliable internet access at home, the skills to use it confidently, or both, and for them the library's computers and staff are often the only route to services that are increasingly digital by default, from job applications to welfare claims. Nor is information online as free as optimists suppose. Much valuable material, from academic journals to newspaper archives, sits behind paywalls, and libraries frequently buy subscriptions that individuals could never afford. To close a library in the name of digital progress is therefore to widen the very gap that technology was supposed to close.

Libraries' own move into digital lending, meanwhile, has exposed an uncomfortable truth about their position. When a library buys a printed book, it owns that copy and may lend it until it falls apart. Electronic books, by contrast, are usually licensed rather than sold, on terms set by publishers. In 2011 the publisher HarperCollins announced that its e-books would expire after being borrowed 26 times, after which libraries would have to buy a new licence, and other publishers have imposed time limits or charged libraries considerably more than ordinary customers. Librarians protested vigorously, and I share their frustration: if the future of reading is digital, the terms on which libraries obtain digital books will determine whether free access survives at all.

None of this means that libraries should stand still. Some of the most successful institutions of recent years look very different from the hushed reading rooms of the past. Oodi, the central library in Helsinki, opened in December 2018 to mark a century of Finnish independence. Alongside its books it offers recording studios, sewing machines, 3D printers and spaces where visitors can simply sit without being expected to buy anything. In 2019, its first full year, it received more than three million visits, comfortably exceeding the number its planners had anticipated. Elsewhere, libraries lend tools, musical instruments and even seeds, host homework clubs and offer advice on matters ranging from health to debt.

Critics object that such services stray too far from the library's core mission and duplicate what other organisations already do. I have some sympathy with this concern. A library that becomes merely a community centre with a few shelves risks losing the expertise that distinguishes it, namely the ability of trained staff to help people find, evaluate and make sense of information. In an age of misinformation, that skill is arguably more valuable than ever. The danger is particularly acute where councils have replaced professional librarians with volunteers. Volunteers can be dedicated and generous, and many libraries would struggle without them, but they cannot be expected to provide the same depth of guidance, and a service that depends on unpaid goodwill is fragile.

What, then, should the library of the future be? In my view, it should be defined less by the objects it contains than by the public space and expertise it provides. It should be one of the few places left where anyone may enter, stay as long as they wish and pay nothing, regardless of age, income or background. It should offer free access to information in whatever format that information takes, and it should employ people qualified to help others navigate it. Printed books will remain central for many readers, particularly children, but they need not be the whole of the offering.

Such libraries will not be cheap, and in hard times they will always be tempting targets for savings. But the costs of closure are real even if they are harder to see in a council's accounts: lonely people with nowhere warm to go, students with nowhere quiet to work, job seekers without access to a computer. A society that values opportunity cannot afford to treat its libraries as a luxury. The question is not whether we need public libraries, but whether we are willing to pay for the kind of libraries we need.