Mona Lisa An artist claims to have cracked a 500-year-old mystery surrounding the Mona Lisa - by spotting a series of zoo animals hidden in the painting. Ron Piccirillo believes it is possible to see the heads of a lion, an ape and a buffalo floating in the air around the subject's head along with a crocodile or snake coming out of the left hand side of her body.
The amateur oil painter and graphic designer based in New York says he followed a series of instructions set out by the artist Leonardo da Vinci to decipher the image and claims his discovery cracks open the meaning of the work, painted in 1519.
That the Mona Lisa is actually a representation of envy.
The theory is likely to lead to controversy among art critics, many of whom having theories of their own about the painting and the Mona Lisa's enigmatic smile.
Mr Piccirillo claims to have found similar hidden images in works by other Renaissance painters such as Titian and Rafael.
It was when he turned the painting on its side that he first noticed the lion's head.
He said: 'Then I noticed the buffalo and I thought: "Oh my God". Then I realised I was really onto something. I just could not believe what I was looking at. I realised, "this is what I've been looking for".'
Mr Piccirillo also said he had found either a crocodile or snake by following the instructions of da Vinci's journals.
Looking at the painting from a 45 degree angle from the left, the path that runs in the scenery behind the Mona Lisa appears almost serpentine.
This was supposedly where the angle of the light was best and led to the least amount of reflection. From a diagram in da Vinci's journals which explained this, Mr Piccirillo called it the 'D-point'.
The instructions also called for the viewer to put their eyes on the same level as the horizon in the painting.
From this he was able to make sense of the line in the passage about how to paint envy which reads: 'Make her heart gnawed by a swelling serpent', as there is such a creature emerging from her right breast.
He then spent two months pouring over the da Vinci's journals before coming up on a passage about envy.
'It's amazing because everyone thought that da Vinci never wrote about the Mona Lisa, but now it appears that he did.'
The passage in question talks about how the artist trying to paint envy must 'give her a leopard's skin, because this creature kills the lion out of envy and by deceit' - a reference to the hidden lion's head.
Once Mr Piccirillo cracked that everything else fell into place.
Mr Piccirillo said: 'This is really about viewing perspective. Imagine standing in front of an oval line drawing. It is obviously an oval, but if you view it from the left or right, at a large enough angle, the oval turns into a circle.
'This is the key to understanding how Leonardo and many other Renaissance artists hid subjects in their artwork. If you know to look for them, they are there.
'I don't know why this has been missed for so long and I can't tell you what it means - that's one for the art historians.
'Da Vinci could have been using horses heads as some kind of religious code, but as to why they are hidden I have no idea.
'It's not every day you spot something that has gone unnoticed for 500 years.'
He added: 'It is not just in da Vinci's works.
'I have seen these hidden images in works by Titian and Rafael and also all over the Sistine Chapel.
Last year Italy's National Committee for Cultural Heritage claimed revealed that magnification of high-resolution images of the Mona Lisa's eyes has revealed letters and numbers.
Infra-red images have also revealed da Vinci's preparatory drawings that lie behind layers of varnish and paint.
Da Vinci began work on the painting in 1503, and it now hangs in the Louvre in Paris in a concrete, climate-controlled bunker where she can only be viewed through two sheets of bulletproof glass set 25 centimetres apart.
The work, also known as 'La Gioconda', is believed to have portrayed the wife of Francesco del Giocondo.
The title is a play on her husband's name, and also means 'the jolly lady' in Italian.