LEONARDO REDUX

By Frederic Golden

Even for a duke of cyberspace like Bill Gates, the price seemed steep. In 1994 he paid the estate of oil baron Armand Hammer $30.8 million for one of Leonardo da Vinci's lesser notebooks. Compared with the Renaissance master's other surviving manuscripts, Codex Leicester (named for the English family that owned it for two centuries) is trifling, just 18 sheets of linen paper folded in half to produce 72 pages. It contains only modest samples of Leonardo's celebrated draftsmanship--no spectacular drawings of flying machines, no cutaways of the human anatomy or exploded views of geared gadgetry. Still, Microsoft's billionaire boss surely got his money's worth. Of thousands of unbound manuscript pages produced by Leonardo (1452-1519), Codex Leicester is the best evidence of his enormous powers as a scientific thinker--and an astonishingly modern one at that.

Gates, who says Leonardo has always been a personal hero, is now letting the world glimpse his treasure. In a stunning exhibition titled "Codex Leicester: A Masterpiece of Science" at New York City's American Museum of Natural History, Leonardo's precious sheets are beautifully displayed in climate-controlled glass cases, illuminated only intermittently to protect the ancient ink and paper, while skilled docents use working models to repeat Leonardo's experiments. At nearby computer terminals, museumgoers view digitized images of the manuscript close up, reading English translations alongside Leonardo's Italian, zeroing in on specific drawings and flipping back and forth between the master's idiosyncratic mirror-image writing and ordinary script. (The left-handed Leonardo wrote backward for comfort--not, as myth has it, for protection against prying eyes.)

His genius leaps across the centuries. When he seeks explanations, for example, of the faint glow between the horns of the crescent moon or the origin of fossils, he is nearly a century ahead of the scientific thought of his day. He correctly attributes lunar light to solar rays reflected from the Earth. Like Galileo, he risks ecclesiastical wrath by rejecting the belief that fossils were deposited on mountaintops by Noah's flood (because, he argues, a deluge would have scattered them helter-skelter rather than leaving them in orderly assemblages). And though his mind-set remains medieval, he demonstrates a decidedly modern curiosity about nature, an openness to theorizing and, above all, a willingness to dispute dogma in lively debates with an imagined "adversary." Had he ever published them, his scientific musings would surely have seemed as revolutionary to his Quattrocento contemporaries as did his ideas on perspective and color.

Leonardo composed the notebook between 1508 and 1510, during a time when he was approaching 60 and shuttling between Milan and Florence, engaged principally as a hydraulic engineer but somehow also finding time to conduct dissections, stage lavish entertainments for his royal patrons and paint his masterpiece, the Mona Lisa. He skips from astronomy to the flight of projectiles, but his major theme is water and its mysterious behavior--its varying flow and pressures, its intersecting currents, its ability to rearrange the countryside.

In Leonardo's day, water was regarded as one of the four basic elements (along with earth, air and fire). He saw it as a major shaper of the earth, circulating in underground caverns and emerging as geysers and mountain springs, and infusing all of life--an idea he often incorporated in his art by painting curls of hair as if they were twirls of a whirlpool. In a premonition of the Gaia hypothesis, which compares the planet to a living organism, he writes poetically, "We may say that the earth has a spirit of growth, and that its flesh is the soil; its bones are the successive strata of the rocks...its cartilage is the tufa stone; its blood the veins of its waters."

He is a born physicist. Anticipating the Dutch scientist Christiaan Huygens by nearly two centuries, he propounds the law of wave motion, suggesting that it is water's "percussive" force rather than water itself that is moving. Sketching a water drop splattering on a flat surface, he catches its precise, crownlike spray in a stop-action image that was not verified until Harold Edgerton's high-speed photography at M.I.T. Impressive too are his moral sensibilities. He mentions that he has invented an underwater breathing device, then notes that divers could use it to sneak up on enemy ships and sink them. So he destroyed it, he says, lest "the evil nature of men" turn it into an instrument of death. Half a millennium later, he clearly remains a man ahead of his time.