Da Vinci sketch under hammer

The da Vinci study is one of the last remaining in private hands

By CNN's Peter Humi

PARIS, France -- A Leonardo da Vinci sketch of a galloping horse is expected to fetch over $5 million when it goes under the hammer.

The auction house Christie's says the piece, which is over 500 years old, is the most significant to come up for sale since the 1930s, being one of the last still in private hands.

Nicolas Schwed of Christie's in Paris told CNN that the Italian master had left many sketches of horses.

"Horses were something particularly difficult to draw for Renaissance artists, because you couldn't really see the movement of horses when they walked. It was too fast," said Schwed.

"The way he did it was to draw different sets of legs, about three or four set of legs at the back to create movement."

The Chairman, Christie's International Fine Art Specialist Group, Noel Annesley, said the study has a "suggestive economy of line."

VIDEO Sketch expected to fetch $5 million (June 9) Play video (QuickTime, Real or Windows Media)

The overall effect, said Annesley is that of: "A jewel-like object with power to transcend its modest scale."

The horse, with a rider, was done in Florence on parchment in about 1480, as a preparatory study for the unfinished Adoration of the Magi painting, now in the Uffizi Museum in Florence.

Completed when da Vinci was in his twenties, the sketch is all the more remarkable because the silverpoint technique, which uses a small block of real silver, meant da Vinci could not actually see what he was doing.

"What's very difficult with this technique is that when you make the drawing you don't see what you draw, you only see it when the silver oxidises which takes a few minutes," Schwed explained.

The sketch goes up for auction in London at Christie's Old Master Drawing sale on July 10th.

Da Vinci, today probably best known for the mysterious Mona Lisa hanging in the Louvre in Paris, was a man head of his time -- a scientist, engineer and theorist as well as a painter and sculptor.