Leonardo da Vinci

The Inexhaustible Subject

Walter Isaacson spent years with Leonardo’s notebooks — more than 7,200 surviving pages of observations, sketches, anatomical studies, engineering designs, and thoughts on everything from the movement of water to the nature of light — and produced a biography that is his most satisfying precisely because Leonardo is the most satisfying subject.

The man who painted the Mona Lisa and The Last Supper was also the most innovative anatomist of the Renaissance, an engineer who designed flying machines, hydraulic systems, and military engineering two centuries ahead of their practical realisation, a botanist, a geologist, a musician. The question Isaacson pursues is not “how could one person have done all this?” — the question is “what do all these things have in common, and what does that tell us about creativity?”

The Notebooks

The primary sources for Isaacson’s biography are Leonardo’s notebooks themselves — journals in which he recorded everything that interested him, in mirror-script that could only be read by holding the page to a looking glass. The notebooks are filled with lists of things Leonardo wanted to know: How does a woodpecker use its tongue? What does the sun look like from the moon? How does language work in the brain? The lists are themselves a kind of portrait.

Isaacson’s key insight about the notebooks: Leonardo’s curiosity was so broad as to occasionally prevent completion. He left many of his greatest projects unfinished, perpetually distracted by related questions. This was simultaneously his limitation and his genius — the relentless interest in understanding prevented the satisfaction that would have stopped the inquiry.

Art and Science as One

The chapter on the Mona Lisa is worth the price of the book alone. Isaacson walks through the painting’s technical innovations — sfumato (Leonardo’s technique of blurring edges to mimic human visual perception), the geological landscape in the background, the mathematical precision of the composition — and connects them to Leonardo’s scientific investigations of light, optics, and anatomy. The painting is both art and knowledge; the two are inseparable.

What Leonardo Teaches

Isaacson ends the book with a chapter of lessons drawn from Leonardo’s life. The one he emphasises most: Be curious about everything. Not everything you’re curious about will be useful. Not all the questions will have answers. But the habit of insatiable curiosity — of noticing things, asking why, following the interest wherever it leads — is what separates great minds from adequate ones.

The Notebooks as Primary Source

Leonardo da Vinci left behind more than 7,200 pages of notebooks — journals in which he recorded observations, sketches, anatomical studies, engineering designs, mathematical investigations, and lists of things he wanted to understand. These notebooks, scattered across collections in Milan, Turin, Paris, Windsor, and Madrid, are the primary source for Isaacson’s biography, and the decision to use them as the spine of the narrative rather than external accounts of Leonardo’s life is the book’s most important structural choice.

The notebooks are extraordinary documents. They contain the preparatory sketches for the Mona Lisa alongside notes on the anatomy of the woodpecker’s tongue. They describe hydraulic systems and military engineering devices alongside observations about the way light falls on a sphere. They contain shopping lists, arguments with patrons, and philosophical speculations about the nature of time. Isaacson reads them as a portrait of a mind in motion — perpetually curious, perpetually distracted, perpetually generating more questions than any finite life could answer.

Leonardo wrote his notes in mirror script — left to right when read in a mirror — a habit sometimes attributed to secrecy and sometimes to his left-handedness. Isaacson inclines toward the latter explanation: mirror script was the natural writing direction for a left-handed person who wanted to avoid smudging fresh ink. Whether this is correct matters less than the notebooks’ content, which Isaacson quotes extensively and analyses with genuine attention to what Leonardo was thinking rather than what he produced.

Leonardo Born April 15, 1452

Leonardo was born on April 15, 1452, in Vinci, a small town in the Tuscan hills west of Florence. He was illegitimate — the son of a notary, Ser Piero da Vinci, and a peasant woman named Caterina — and this illegitimacy shaped both his opportunities and his intellectual formation. Unable to attend the Latin schools that prepared students for university, he was apprenticed to the painter and sculptor Andrea del Verrocchio in Florence, where he received practical training in drawing, painting, sculpture, and the mechanics of workshop production rather than the classical education of his legitimate contemporaries.

Isaacson argues that this background was a precondition of Leonardo’s particular genius: the absence of formal academic training meant that Leonardo approached every subject empirically rather than through established doctrine. He observed before theorising, questioned before accepting authority, and remained willing to revise conclusions that contradicted his observations. These habits, instilled partly by circumstance and partly by temperament, are the source of both his scientific achievements and his artistic innovations.

The Mona Lisa Explained

Isaacson’s analysis of the Mona Lisa is worth dwelling on because it demonstrates the method of the whole book: connecting the technical achievement to the scientific investigation that produced it. The painting’s most famous quality — the subject’s expression, which seems to change depending on where you look — is the result of Leonardo’s understanding of the physiology of human vision. The eye’s peripheral vision, which processes shape and motion differently than its central vision, reads the corners of the mouth as a smile when it processes the overall face; direct focus on the mouth finds the expression more neutral. Leonardo knew this because he had studied the eye anatomically, and he exploited it in paint. The Mona Lisa is a technical demonstration of optical science rendered as art.

Lessons Isaacson Draws

The concluding chapter of the biography offers lessons from Leonardo’s life, and the most important is also the most transferable: cultivate insatiable curiosity and follow it wherever it leads, even when it leads away from what you are supposed to be doing. Leonardo’s notebooks are full of investigations that had nothing to do with any commission he was working on; the investigations are why his commissions, when he completed them, were unlike anything anyone had done before. The curiosity was not a distraction from the work. It was the work.

Final Verdict

Leonardo da Vinci is Isaacson’s best biography — a fitting tribute to the most inexhaustible subject in the history of human achievement.

Our rating: 4.6/5 — A joy to read. Isaacson and Leonardo together produce something genuinely inspiring about the possibilities of human curiosity.

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