Walter Isaacson writes biographies of people who are inherently interesting. This is less common than you'd think. Happily, his new "Leonardo da Vinci" (Simon and Schuster) is worthy of its subject. His prose is scoured of hyperbole because none is needed. His subject is among the handful of history's indisputable geniuses, and merely to describe Leonardo accurately - as Isaacson does as much as is possible with a figure from the 15th century - yields a colorful man, as engaging as engaged.
Leonardo's longest-term intimate relationship was with a Milanese boy he nicknamed Salai, who from the start stole from the artist, studied with him only half-heartedly and offended far more of Leonardo's friends than he ingratiated himself to. Although Leonardo may have enjoyed sexual intimacies with others - wholly unsurprisingly, he took to the pretty young ones with curly hair like his own - he kept Salai's company and looked after him until the end.
If the 15th century had had Prozac, Lithium and Adderall, we might not have had "The Last Supper" or "Mona Lisa," though Leonardo's generously recombinant family (he was born illegitimate, not always a disadvantage then, and not in Leonardo's case) seemed vastly more charmed than vexed by his insatiable curiosity, strangely alloyed with a steak of laziness, or something that look like it. He left unfinished far more projects than he sketched or painted; you could write that off as perfectionism or admire its tireless quest for greater clarity.
I wonder if, in our techie times, his drawing of the "Vitruvian man" - the handsome nude with two arms and two legs, overlaid and touching the edges of the circle and the equal-volume square that contain him, or on which he rides like a circus performer - is not the avatar that "says" Leonardo more than the "Mona Lisa." If the face and physiognomy are not a self-portrait, they reflect what was said to be his strikingly handsome face, curly hair and beautifully proportioned, naturally muscled body. He moved with grace, movement itself his among his greatest obsessions.
Isaacson's biography is linear enough to follow easily, yet it returns, as did the artist, time and again, to the highly concrete, enticingly yet rigorously investigable mysteries of the human and natural world. Isaac's view of Leonardo's homosexuality is itself a model. Many of us have fought through weighty studies of more outrageous geniuses, to find only a paragraph or maybe a subsection on the homosexuality.
"Leonardo was sexually and romantically attracted to men and, unlike Michelangelo, seemed to be just fine with that," Isaacson chirps, directly and easily. "He made no effort either to hide or proclaim it, but it probably contributed to his sense of being unconventional."
Had he not been as enticing an eccentric, who knows what would have been made of his comparatively outlandish dress? Long garments were the fashion of the day, but Leonardo's typically stopped at mid-calf and were, when not lavender, pinkish.
Isaacson shares his subject's distaste for the rougher aspects of Michelangelo (which is to say, most of them), an intermittent rival. Speaking only for myself, "Art" hasn't been the same since I saw - unexpectedly, in an instant; an Italian friend was playing a trick - Michelangelo's "David" in Florence. So I found it more than a little starling to read that Leonardo was one of the loudest proponents of moving the statue indoors - and adding the "fig leaf," which effectively nicked David's dick for decades.
It's difficult to see anything but rivalry of the most virulent sort from Leonardo, a painter and sketcher who drew many a male nude devoid of self-censorship. Early on, Isaacson notes, "In a section of his notebooks called 'On the penis,' [Leonardo] described quite humorously how the penis had a mind of its own and acted at times without the will of the man."
The "notebooks" provide the substance of this biography. Some 7,200 pages of them, thought to represent a quarter of the total, survive. They have, Isaacson says, "been rightly called 'the most astonishing testament of the powers of human observation and imagination ever set down on paper.'"
"His curiosity, like that of Einstein [the subject of another Isaacson biography], often was about phenomena that most people over the age of 10 no longer puzzle about: Why is the sky blue? How are clouds formed?"
"Leonardo had set for himself the most magnificent of all tasks for the mind of mankind: nothing less than knowing fully the measure of man and how he fits into the cosmos," Isaacson writes.
Some of the designer-painter's personal favorite art came by way of his complete plans for elaborate palace pageants, on which he lavished infinite, loving care. None was expected to last past dawn.
The surviving art is considered in-depth, culmination with what Isaacson deems the masterpiece, the "Mona Lisa." Leonardo carried it with him for years, across Italy and eventually to Paris, always refining it, and never selling it.
"At the time when he was perfecting Lisa's smile, Leonardo was spending his nights in the depths of the morgue under the hospital of Santa Maria Nuova, peeling the flesh off cadavers and exposing the muscles and nerves underneath," Isaac adds. "He became fascinated about how a smile begins to form and instructed himself to analyze every possible movement of each part of the face."
This beautiful book, on coated stock, showing text and illustrations to the best advantage, is a pleasure to hold. Leonardo, whose interest in politics was slight, would have approved of it.
Walter Isaacson will be appearing Oct. 24, 7 p.m. at the San Francisco JCC (3200 California St.): jccsf.org/arts-ideas/walter-isaacson/, and Oct. 25, 7:30 p.m. at Kepler's Books, Menlo Park: brownpapertickets.com/event/3016070.
"Leonardo da Vinci" author Walter Isaacson with the "Vitruvian man." Photo: Courtesy Simon & Schuster