There have been, of course, many other insatiable polymaths, and even the Renaissance produced other Renaissance Men. But none painted the Mona Lisa, much less did so at the same time as producing unsurpassed anatomy drawings based on multiple dissections, coming up with schemes to divert rivers, explaining the reflection of light from the earth to the moon, opening the still-beating heart of a butchered pig to show how ventricles work, designing musical instruments, choreographing pageants, using fossils to dispute the biblical account of the deluge, and then drawing the deluge. Leonardo was a genius, but more: he was the epitome of the universal mind, one who sought to understand all of creation, including how we fit into it.

Leonardo had almost no schooling and could barely read Latin or do long division. His genius was of the type we can understand, even take lessons from. It was based on skills we can aspire to improve in ourselves, such as curiosity and intense observation. He had an imagination so excitable that it flirted with the edges of fantasy, which is also something we can try to preserve in ourselves and indulge in our children.

...the most sublime of oddballs, Leonardo da Vinci

Leonardo was not always a giant. He made mistakes. He went off on tangents, literally, pursuing math problems that became time-sucking diversions. Notoriously, he left many of his paintings unfinished, most notably the Adoration of the Magi, Saint Jerome in the Wilderness, and the Battle of Anghiari. As a result, there exist now at most fifteen paintings fully or mainly attributable to him. Although generally considered by his contemporaries to be friendly and gentle, Leonardo was at times dark and troubled. His notebooks and drawings are a window into his fevered, imaginative, manic, and sometimes elated mind. Had he been a student at the outset of the twenty-first century, he may have been put on a pharmaceutical regimen to alleviate his mood swings and attention-deficit disorder. One need not subscribe to the artist-as-troubled-genius trope to believe we are fortunate that Leonardo was left to his own devices to slay his demons while conjuring up his dragons.

Leonardo is the Hamlet of art history whom each of us must recreate for himself.

In addition to his instinct for discerning patterns across disciplines, Leonardo honed two other traits that aided his scientific pursuits: an omnivorous curiosity, which bordered on the fanatical, and an acute power of observation, which was eerily intense. Like much with Leonardo, these were interconnected. Any person who puts “Describe the tongue of the woodpecker” on his to-do list is overendowed with the combination of curiosity and acuity. His curiosity, like that of Einstein, often was about phenomena that most people over the age of ten no longer puzzle about: Why is the sky blue? How are clouds formed? Why can our eyes see only in a straight line? What is yawning? Einstein said he marveled about questions others found mundane because he was slow in learning to talk as a child. For Leonardo, this talent may have been connected to growing up with a love of nature while not being overly schooled in received wisdom.

Kenneth Clark referred to Leonardo’s “inhumanly sharp eye.” It’s a nice phrase, but misleading. Leonardo was human. The acuteness of his observational skill was not some superpower he possessed. Instead, it was a product of his own effort. That’s important, because it means that we can, if we wish, not just marvel at him but try to learn from him by pushing ourselves to look at things more curiously and intensely. In his notebook, he described his method — almost like a trick — for closely observing a scene or object: look carefully and separately at each detail. He compared it to looking at the page of a book, which is meaningless when taken in as a whole and instead needs to be looked at word by word. Deep observation must be done in steps: “If you wish to have a sound knowledge of the forms of objects, begin with the details of them, and do not go on to the second step until you have the first well fixed in memory.

That goes a step too far, I think. Leonardo did not invent the scientific method, nor did Aristotle or Alhazen or Galileo or any Bacon. But his uncanny abilities to engage in the dialogue between experience and theory made him a prime example of how acute observations, fanatic curiosity, experimental testing, a willingness to question dogma, and the ability to discern patterns across disciplines can lead to great leaps in human understanding.

To Leonardo a landscape, like a human being, was part of a vast machine, to be understood part by part and, if possible, in the whole. Rocks were not simply decorative silhouettes. They were part of the earth's bones, with an anatomy of their own, caused by some remote seismic upheaval. Clouds were not random curls of the brush, drawn by some celestial artist, but were the congregation of tiny drops formed from the evaporation of the sea, and soon would pour back their rain into the rivers.

The oft-heard comment that Leonardo [da Vinci]'s genius managed to transcend the culture of his time is amply justified. But his was not a science-fiction voyage into the future as much as a plunge into the past.

Gargoyles were the complement to saints; Leonardo's caricatures were complementary to his untiring search for ideal beauty. And gargoyles were the expression of all the passions, the animal forces, the Caliban gruntings and groanings which are left in human nature when the divine has been poured away. Leonardo was less concerned than his Gothic predecessors with the ethereal parts of our nature, and so his caricatures, in their expression of passionate energy, merge imperceptibly into the heroic.

He found him a tall figure, with a slightly flabby body, shining hair and well-trimmed beard. He appeared impressive, well-dressed and his eyes were exceptionally eloquent that drew everyone’s attention. There was deep note of mystery about his eyes...His style of conversation was always accompanied by his smile and too attractive which cast a spell on his addresses...He had a remarkable ability to assess others and immediately found out their mental level and their taste. Likewise, he had an enviable understanding of the context and situation in which he found himself placed.

"But Italy worked some marvel in her. It gave her light, and – which he held more precious – it gave her shadow. Soon he detected in her a wonderful reticence. She was like a woman of Leonardo da Vinci's, whom we love not so much for herself as for the things that she will not tell us. The things are assuredly not of this life; no woman of Leonardo's could have anything so vulgar as a "story." She did develop most wonderfully day by day."

He was a young man of pleasant appearance. Of medium height and exceedingly pale, he was nevertheless strongly built and quick and easy in his ways. Save for his deafness in one ear, his physical health was perfect. Handsome as he was, he was given to long silences. So girls didn't know what to make of him. But men liked him. After a while they saw that he was easy and meant no harm. He was the sort whom classmates remember fondly; they liked to grab him around the neck with an elbow and cuff him around. Good-looking and amiable as he was, however, he did not strike one as remarkable. People usually told him the same joke two or three times.