Our regular look at some of the faces which have made the news this week. Above are MONA LISA(main picture), with BILL CLINTON, VICTORIA COREN, ROSELANE DRIZA and LORD LINLEY.
Theories about what lies behind the Mona Lisa's famously enigmatic smile appear regularly every few years.
In this century alone, scientists have attributed it to a trick of the light, to a trick of the human eye, that she was constipated and, this week, to the suggestion that she was in the family way.
French scientists say that, by laser scanning, they have uncovered a fine gauze veil on the dress of Leonardo da Vinci's most famous muse. This was something that either soon-to-be or new mothers wore in 16th Century Florence.
It's not the first time the pregnancy theory has been aired. In 1959, a British doctor insisted the Mona Lisa had a "puffy neck" caused by an enlarged thyroid gland, a sure sign of impending motherhood.
The enigma of her smile is summed up in the Italian word sfumato. It means ambiguous, nebulous, up to the imagination. This is why, for many, Mona Lisa smiles with her eyes, rather than her mouth.
Sigmund Freud saw the "smile" as signifying Leonardo's erotic attraction to his mother. Others interpret it as a sign of innocence.
Mona Lisa is sometimes also known as La Giaconda because she was believed to be Lisa Gherardini, the wife of the wealthy Florentine silk merchant, Francesco del Giocondo.
In Italian, Giocondo also means light-hearted, as in jocund in English. So, because of her smile, this name has a double-meaning: a trick of the tongue, you might say.
This parody is made from burnt toast
There have been many theories too as to the Mona Lisa's identity. In 2002, one art historian named her as the Italian Countess Caterina Sforza, a famous courtesan who probably died of syphilis. No smiling matter there.
Previous theories mused that she was Leonardo's mother, various members of the Italian aristocracy, a feminised version of Leonardo himself and, less seriously, a distant ancestor of Sonia from EastEnders.
Research in 2004, however, backs the original Lisa Gherardini theory. It was recently discovered that Leonardo's father knew Lisa's father very well and her portrait was probably commissioned by him.
Aged 24 when Leonardo began painting her in 1503, she outlived her husband and bore five children. The artist was still working on the painting when he emigrated to France in 1516 and is believed to have finished it three years later, just before he died.
The painting has remained in France ever since and is owned by the state. It once hung in Napoleon's bedroom.
In artistic terms, the Mona Lisa is famed for its simplicity and for the subtlety of the transitions of tone and colour. The landscape behind the subject, the rocks of the Arno valley and the winding river and road, are echoed in the lines of her veil and hair.
This is taken to represent the Renaissance idea that the human form is a part of the earth itself, and a microcosm of God's creation. It enabled Leonardo to exhibit the genius of his sfumato techniques.
Yet, amid so many painting masterpieces, how did the Mona Lisa get to become the most famous painting in the world? Why do six million people flock to the Louvre in Paris to see it each year?
It was largely forgotten until the 19th Century Symbolist movement made much of it, interpreting it as an embodiment of femininity and female mystique.
Many viewers are disappointed at the Mona Lisa's small size
Then, in 1911, its fame increased when it was stolen from the Louvre in order that copies could be made by an expert forger and sold as the original. This never took place and the painting was recovered two years later when the thief tried to sell it.
In 1956, its stock increased further when someone threw acid at it, badly damaging part of it. In the same year someone else threw a rock at it.
By now it had become a cultural icon, the ultimate expression of beauty, the subject of countless popular songs as well as parodies, most notably by the Dadaist painter Marcel Duchamp, and by the pop artist Andy Warhol.
The painting was even used as a diplomatic device. When tensions arose between the US and France in the early 1960s, the Mona Lisa was lent to America as a gesture of goodwill, and was famously visited by Jackie Kennedy.
Later, it toured Japan and the Soviet Union.
Somehow the Mona Lisa's artistic merit appears to have got buried in the avalanche of seemingly endless analysis of its subject's identities and the mechanics of her smile.
Such is the plethora of oversized reproductions of it that most tourists seem disappointed when they see how small it actually is, according to museum staff.
Yet it is the enigma that is the Mona Lisa that will see it continue as an object of fascination, sheltering it from the ever-changing perceptions of beauty.
Former US president Bill Clinton sauntered on to the stage at the Labour Party conference in Manchester this week to lend his folksy charm and wisdom to the proceedings. He was full of praise for Tony Blair and Gordon Brown. "I saw Gordon's brilliant vision of the future and I heard the Prime Minister's magnificent valedictory," he said before expounding on global issues such as the environment, poverty and terrorism.
The author, journalist and television presenter, Victoria Coren, became £500,000 richer this week after becoming the first woman to win one of the most prestigious events in the international poker calendar. She beat 400 other players from more than 30 countries to take the top prize in the London leg of the European Poker Tour. "I was totally dazed and shocked," said 33-year-old Coren, daughter of humorist Alan Coren.
In a sensational London court case, a Brazilian woman, Roselane Driza, was convicted of blackmailing a woman judge and stealing two videos from a male judge with whom she was having an affair. The video reportedly showed the two judges having sex. Driza made a £20,000 blackmail demand to the woman judge after being sacked as her cleaner. She claimed that both judges knew she was in Britain illegally when they employed her. They denied this.
The Queen's nephew, Lord Linley, got into hot water this week after he was photographed taking his four-year-old child to school on the back of his bicycle. The picture showed young Margarita perched on the back rack of his folding bike with her coat tails dangerously close to the rear wheel. His excuse was that he was waiting for a new bike to be delivered complete with proper child seat.
Written by BBC News Profiles Unit's Bob Chaundy