Voltaire and Catherine the Great: a pair of unlikely pen-pals

A unique set of correspondence between the Russian Empress Catherine the Great and the French philosopher Voltaire has been bought by an unknown Russian patriot "for the good of the country". The extravagant gesture, at a Sotheby's auction in Paris, set a new record for the price anyone has paid for 18th-century correspondence - in this case £400,000 for 26 letters.

The letters had been expected to be sold for half of that sum but became the object of a fierce bidding war between the mystery buyer and a Russian businessman based in America.

In Russia, the purchase is being compared to the acquisition in 2004 of nine Fabergé eggs by the oligarch Viktor Vekselberg, a grand gesture that brought back part of Russia's fabulous cultural legacy to the Rodina or Motherland. The 26 letters may not have had the eye-watering £60m price tag that the gem-encrusted eggs boasted, but their rarity combined with speculation about the identity of their buyer has ensured a stir of equal proportions.

"Eggs, letters - what's next?" asked the daily Nezavisimaya Gazeta, discussing the growing trend to procure cultural treasures for the good of Russia, a gesture that tends to endear the patriot in question to the Kremlin and public opinion alike. The paper suggested that the letters had been bought on the orders of a senior government official but it was unclear whether the money used to buy them was his own or the state's.

Interest in the collection is considerable because Catherine the Great, a German-born princess, is Russia's most famous female ruler, and Voltaire one of France's pre-eminent Enlightenment philosophers. They corresponded for 15 years until Voltaire's death, and though they never met became firm friends and mutual admirers. Voltaire called Catherine "The Star of the North" and the "Semiramis of Russia" in a reference to a legendary Queen of Babylon.

Bought by a Moscow-based art dealer on behalf of the unknown philanthropist, the letters used to belong to the Rothschild family and amount to a quarter of the pair's correspondence. Their contents have never been published, and are something that many of the world's greatest museums would gladly display. The remaining letters between Catherine the Great and Voltaire are stored in the state archive in Moscow and in the National Library in Paris.

Alexander Khochinsky, the Russian art dealer who bought the letters on behalf of the mystery buyer, said he had done so for Russia's sake but denied the buyer was an oligarch.

"The idea is very patriotic," he said. "The purchase is linked with those genuine thoughts in mind. The letters will return to Russia." The letters date from 1768 to 1777, and in some of them Voltaire signs himself off as "the old hermit" or simply as "V". The two friends discuss Catherine's foreign policy, including the partition of Poland and her first war with the Ottoman Empire in 1768-74. In the letters, Voltaire exercises his famous wit to refer to the Ottoman ruler, Mustafa III, as "fat and ignorant".

The world's great givers

* Viktor Vekselberg, 45, head of Russia's third-largest oil and gas company, became a national hero after bidding an astonishing £60m for nine Fabergé eggs from the American Forbes family. Peter Carl Fabergé originally made 57 eggs for Russia's Tsars.

* On Tuesday, Steve Wynn, a billionaire businessman, paid £5.3m for a 600-year-old early Ming vase at a Christie's auction. Rather than send it to his art collection, displayed at his Las Vegas hotels, the casino magnate donated it to a museum in Macau.

* The record for the world's largest philanthropic donation is held by none other than the world's richest man - Bill Gates, left. In 1999, the head of Microsoft gave $3.34bn (£1.79bn) to fund healthcare initiatives around the world.

Jerome Taylor