Tea will cure your lumbago and strengthen your frail and nervous constitution. It will enhance your virility and cause your you-know-what to grow. It prevents hangnails and may even aid in cases of boanthropy, the bizarre and often mistaken belief that one is a cow.

What's most interesting about the exalted claims regarding tea's health benefits, if we're to believe Laura Martin, is how everything old is new again.

The prevailing, and just a little bit too quaint, explanation for the origin of tea goes like this. Some time around 2,700 B.C.E., the Chinese Emperor Shen Nung, who was apparently a bit of a clean freak, was boiling water for drinking. Lo and behold, some tea leaves wafted over on the breeze and landed in his kettle. How convenient. Shen Nung took a sip and wowie zowie...it was tea time for the world. In reality, Martin notes, Shen Nung was probably a creation of legend and humans may have already been drinking tea for about half a million years.

We know that the Chinese have been drinking tea for a long time, first brewing it with leaves from tea trees growing in the wild. Beginning sometime around the first century, they started taking their tea leaves from cultivated trees. Not long after, the Chinese began processing their tea before drinking it, which improved the taste of what had been a bitter, unpalatable brew.

Not that taste was of paramount concern at the time. For then, as now (at least for many recent converts to tea drinking), the brew was valued more for its medicinal value than taste. Then as now, some rather extravagant claims were made for tea as a tonic.

People have been writing books about tea since Lu Yu published the Ch'a Ching (Tea Classic), in 780. In telling tea's story, it's inevitable that today's authors will tread some familiar ground. Martin does so, to be sure, but also manages to unearth some nuggets of tea knowledge not often touched upon.

In China, Martin tells us, tea became entrenched during the T'ang Dynasty. During the Song Dynasty, some varieties produced for the emperor were said to be more valuable than gold. From China, tea moved to Japan, which codified the notion of tea drinking as a meditative ritual, a practice that had begun in China.

The British thirst for tea and tea profits is legendary. It led them to force their Indian subjects to plant opium poppies, often in lieu of food crops, and peddle the drugs to the increasingly wasted Chinese in exchange for tea.

This insatiable thirst also led the Brits to cut out the middlemen and begin growing tea in India's Assam region. They eventually succeeded, but the immense profits came at the expense of native workers, who were often treated more like slaves than employees. In 1840, the British produced 5,000 pounds of tea in Assam, with considerable difficulty. In 1888, India produced 86 million pounds of tea, outstripping the Chinese for the first time.

By now many tea drinkers prepared the drink by steeping the leaves. In the early days, tea had been pressed into an easily transported and traded brick and a bit was shaved off when it was time for a cup or three. After that - and to this day in the Japanese tea ceremony - powdered tea was whipped into a potent froth of the type said to have helped the monk Bodhidharma endure a nine-year bout of meditation.

Tea came to Europe in 1606 and London in 1657. Prices were exorbitant at first, but became more reasonable as supply lines were established. Even so, at one point the average working class British household was spending about ten percent of its food budget on tea and sugar.

The British also took tea to Ceylon, now Sri Lanka, where Sir Thomas Lipton built an empire that made his name synonymous with the drink. The British also began growing tea in their African colonies, many of which are still key producers to this day.

It's interesting to note that the Dutch brought tea to the New World ten years before it surfaced in London. Of course, the colonists here expressed their distaste for the Crown's oppressive tea taxes in memorable fashion. As a result, tea in the U.S. went out of fashion for a while, but made something of a comeback when American clipper ships began importing the leaf.

America's most notable contribution to tea drinking, though some scorn it, was iced tea, which probably came about in the early nineteenth century. Early on, American tea drinkers drank more than their fair share of green tea - about 40 percent - a number that dwindled as low grades of black tea in bags became ubiquitous.

Tea fanciers fondly note that it's the second most consumed beverage in the world, after water. As a nation, Indians drink the most, while the Turks drink the most per capita. Tea has made positive contributions to humankind, notably in forcing people to boil water that might otherwise harm them. But even today, as Martin notes, "the cost to others when we purchase such commodities is much steeper than the price we pay for them."

It might seem grandiose to posit that the world was changed by a drink many of us still equate with blue-haired and red-hatted ladies of a certain age. But the notion is not that farfetched. It's on this point that Martin's slim book falters ever so slightly, but only by trying to be a bit too comprehensive. The author seems to want to touch on every aspect of tea culture and history in less than 300 pages and can only delve so deeply into the notion that tea changed the world.

Not that she doesn't give it the old college try. Those looking for additional insight into how tea changed Britain and India, might also want to consult - for starters - Tom Standage's chapter on tea and Britain, in A History of the World in Six Glasses, and Alan MacFarlane's Empire of Tea.