Leonardo da Vinci's Madonna with the Yarnwinder is without doubt one of the most famous paintings in the world, but critics are divided about its merit as a work of art.
The painting is one of the most famous in the world
The 500-year-old masterpiece, which was stolen from Drumlanrig Castle in south west Scotland on Wednesday, has been valued by experts at between £25m and £50m.
Edinburgh-based art expert Ricky de Marco said: "I love this painting, it is one of the reasons I believe Scotland is a civilised country.
"Scotland having this painting has the right to call itself truly European.
'Down to earth'
"It's a glorious thing and it is part of a great collection and it's in the most beautiful house imaginable, the perfect place for you to experience a Leonardo.
"It reminds me of the Madonna that it is in the great collection of the city gallery in Krakow, it shows the Madonna in a light which is bringing her as it were down to earth.
"She's involved in the kind of task that mothers are involved in looking after children.
However Brian Sewell, art critic of the London Evening Standard, said it was "not the most desirable" of pictures.
He said: "Technically it is not very sound. It has darkened and cracked with age and much of the drawing of the Madonna's face is really rather grotesque."
Mr Sewell said it was a significant painting in the sense that it was part of the history of Leonardo's art.
He said the picture was disputed by many experts.
"The general opinion is that it was begun by Leonardo, who laid down the original ideas expressed in it, and then later, probably after his death, it was concluded by one of the assistants in his studio," he said.
Professor Duncan Macmillan curator of the Talbot Rice Gallery in Edinburgh said the chances of selling the painting straight away were "nil".
He said: "I think the reputation that works of art are worth a lot of money is something that attracts thieves.
'Madness or greed'
"It is the top name. You can't do better than Leonardo. He is one of the greatest and one of the most famous of all painters."
Mr Sewell said there was no market for the painting because it was "too famous".
"It is widely known by anyone who has ever shown any interest in Leonardo."
Mr de Marco called the theft "the most terrifying madness".
He said: "Whoever has it now in their possession is doomed to look after it in secrecy.
"They are in a state of madness or greed. It is such a beautiful thing, it deserves to be in the hands of people who understand and value it."
"It is now in the hands of people who put it at risk."