If Giorgio Vasari extolled Leonardo da Vinci as a celestial genius, Walter Isaacson brings this most singular artist, engineer, and scientist back to earth. Author of best-selling biographies of Steve Jobs and Benjamin Franklin, Isaacson offers his readers a portrait of the artist as an avatar of passionate curiosity.

While Michelangelo has attracted numerous biographers—Vasari, Condivi, Symonds, Papini, Hirst, and Wallace, to name but some of the earlier and more recent chroniclers of the sculptor's life—Leonardo has not. This difference reflects the nature of the sources available for each. Michelangelo left a trove of letters, poems, and financial records, all of which have been reproduced in modern editions and translated into English. But there is no edition of the voluminous record of Leonardo's preoccupations contained in the 7,200 pages, many written in his famous mirror script, of his notebooks. Taking a different tack than earlier biographers, who tended to focus on the painter's works of art, Isaacson examines Leonardo's life through the notebooks. The result is a monument to “the greatest record of curiosity ever created.” Ever intent on showcasing the way in which Leonardo's scientific and artistic interests intersect, Isaacson delves into Leonardo's Wunderkammer of interests—architectural pursuits, productions of plays and pageants, literary amusements, bird-watching activities, mathematical explorations, studies of water, vegetation, anatomy, perspective, and optics, and inventions of musical instruments, flying machines, and military weaponry. Isaacson breaks down each of these pursuits, all the while pointing out analogies Leonardo found between phenomena as disparate as hair curls and waves of water. In such instances the story often gives way to lists of phenomena, each section a testimony to Leonardo's restless mind, ingenuity, and relentless curiosity.

Describing innovations such as a needle-grinding machine or a water screw intended to illustrate the concept of perpetual motion, however, is a daunting task. The marvel is the intricacy of the drawing itself. Prose description, unless rendered by a writer possessed of an exceptionally dynamic style, has the effect of dulling the fascination of Leonardo's inventions. The biography is absorbing, but readers might prefer to read these sections in stints.

Isaacson seldom ventures aesthetic judgments of his own. In describing works such as the The Annunciation, Madonna and Child with Flowers, Ginevra de’ Benci, and The Adoration of the Magi, he relies on Leonardo specialists, citing amply from studies by Kenneth Clark, Martin Kemp, Carmen Bambach, and other art historians. Leaving it to the experts, especially in this case, serves Isaacson well. Isaacson often expands their claims with citations from the notebooks on how to draw hair, a smile, water, lines, shadows, and other phenomena. These are some of the most engaging parts of the biography: the author deftly presents Leonardo's artistic virtuosity in the painter's own words. In discussing the luster of Ginevra de’ Benci's curls, for example, Isaacson adds an elucidation from the notebooks that reveals that spots of luster will shift and “appear in as many different places on the surface as different positions are taken by the eye” (66). We have the glorious artifact and the observation or theory that informs it. Other lively sections include Isaacson's account of the diverse personages living in Florence when Leonardo arrived in the city, in 1472; the engrossing efforts to authenticate La Bella Principessa; the presence of Cesare Borgia, Machiavelli, and Leonardo in Imola, in the autumn of 1502; and the discussion of the range and depth of Leonardo's to-do lists (get the measurement of the sun promised me by Maestro Giovanni Francese, describe the tongue of the woodpecker).

Early modern specialists will find other sections less compelling—for example, Isaacson's account of the rivalry between Leonardo and Michelangelo, one social and handsome, the other unattractive and antisocial, and the contemporary observation that the realism of The Lady with an Ermine offers an example of a portrait that does all but speak. But such factors do not detract from Isaacson's splendid achievement, at once a magisterial biography and tribute to every aspect of Leonardo's observatory prowess. The book is magnificently produced, with ample reproductions, an illustrated timeline, and an uplifting conclusion on how we can all learn from Leonardo's omnivorous curiosity.