Artist Ron Piccirillo claims he found the heads of a lion, an ape and a buffalo hovering in the air in the background of the Mona Lisa, after turning the painting on its side. (Photo Credit: Associated Press)

New York artist Ron Piccirillo is claiming to have unlocked the secrets behind one of the most mysterious faces in history - Mona Lisa.

Piccirillo argues that several animals can be seen hidden in the painting when it is set horizontally. The Rochester graphic designer and painter said a lion, ape and buffalo can be seen around Mona Lisa's head and a snake or crocodile is near her right shoulder.

The animals led Piccirillo to Leonardo da Vinci's journals and a few passages that mention the animals he sees.

"When I came across these answers, which I call the 'accidental discovery,' I wasn't seeking the information," Piccirillo told ABCNews.com. "I was just able to pull out a lot of puzzle pieces together that led me to the answers. It all came from Leonardo's writings."

One of the passages that references "her heart gnawed by a swelling serpent" also says, "Give her a leopard's skin, because this creature kills the lion out of envy and by deceit." Though the passage does not mention the "Mona Lisa" specifically, Piccirillo said he believes the references to the serpent and the lion lead back to the painting and back to the woman with the infamous smile.

Piccirillo said he believes that Mona Lisa was not an actual person, but, rather, symbolic of the human trait of envy. He also believes that his discovery will be important to an art community that has been puzzled by the painting for centuries.

"I was definitely aware of how big the impact would be in the art world," he said. "I knew it was going to be the biggest thing in 500 years."

Members of the art community do not necessarily agree with Piccirillo's sense of the importance of his discovery.

"I don't believe there's any reason to dwell on this particular theory," Brown University art history professor Evelyn Lincoln told ABCNews.com. "It doesn't help me understand the Mona Lisa to think of her as hiding iconographic symbols that are rather disconnected of envy."

Lincoln called the theory "problematic" and said that the interpretation may have more to do with the viewer than the painting itself. She pointed out that the image people are looking at is not the original painting and that even the original has been worn down by time, with crack and oil.

Lincoln also noted that da Vinci's journals themselves are fragmentary and were put back together after his death.

"The idea that we should be turning the painting upside down and around for an odd iconographic rendition of envy seems to be a personal obsession that this particular graphic artist seems to find in every painting he looks at," Lincoln said. "It's not my Mona Lisa."

Still, Piccirillo said he is confident in his assessment and his theory.

"I've been an artist all my life and always been aware of the mysteries of the Mona Lisa, but I was never that interested in it. I was more interested in the beauty of the art itself," he said. "But once you know what to look for, it's there."