If writing a biography is difficult, writing a biography of someone deemed a ‘genius’ is positively perilous. The danger of producing hagiography is all too real, and all too familiar in the history of the genre. The locus classicus for such hagiography is the treatment of Raphael, Leonardo da Vinci and Michelangelo in Giorgio Vasari’s Lives of the Artists (1550). It is not difficult to draw a direct line from Vasari’s celebration of such ‘divine’ artists to the stratospheric sums paid for their works, epitomised by the recent sale for $450m of a painting (possibly) by Leonardo, Salvator Mundi.

The fear of becoming a modern Vasari has never fazed Walter Isaacson, former chairman of CNN and managing editor of Time magazine, who has written biographies of Steve Jobs, Albert Einstein and Benjamin Franklin, among others. Now he has turned his hand to Leonardo himself, for whose boundless curiosity he has an infectious reverence and passion.

In one way, however, the situation here is rather different from Isaacson’s previous biographies. There, he had access to vast amounts of personal documents (and, in the case of Jobs, to scores of interviews with him and those who knew him). Leonardo famously kept copious notebooks, replete with beautiful diagrams and notes in his left-handed mirror writing, and we are fortunate that a sizeable portion of them has survived. But while these reveal a great deal about his phenomenally wide-ranging interests, they do not offer much for the biographer looking for psychological or personal insights. Indeed, even the most eminent Leonardo scholars admit that our knowledge of such basic questions as the chronology of the composition of the paintings (including the Mona Lisa) remains limited. How can the biographer get past this impasse?

The most excitable of them – and there have been many – have taken the lack of relevant evidence as a licence to give free rein to their most fanciful psychoanalytical or esoteric instincts, whether concerning Leonardo’s status as an illegitimate child, his homosexuality or the supposed clues he left us in his paintings. To his credit, Isaacson for the most part resists such urges. Rather, his solution to the biographer’s problem is simple: to focus almost entirely on Leonardo’s works.

Indeed, the book at points reads almost like an enthusiast’s attempt to catalogue everything Leonardo ever did. This is by no means a bad thing. Isaacson is up to speed with the latest discoveries, from the definitive identification of Leonardo’s mother earlier this year, to the relatively early drawing of St Sebastian that was brought to a small French auction house in 2016, to the results of the infrared analyses that have helped date the two different versions of The Virgin of the Rocks. He does a good job of reminding readers that Renaissance art was almost always collaborative and of explaining how workshop collaboration actually worked. Above all, he conveys well the sense of his subject as an irrepressible perfectionist who could almost never finish the projects that hopeful patrons kept commissioning – among them the huge equestrian statue for Ludovico Sforza of Milan, the vast painting of the Battle of Anghiari for what is now the Palazzo Vecchio during his second period in Florence, and a scheme to divert the River Arno.

Perhaps most illuminating is Isaacson’s comparison of Leonardo’s theoretical statements about painting in his notebooks with their application in those artworks that have survived. Isaacson’s own art historical analyses are bold and he goes so far as to disagree with renowned specialists. For example, he insists that the uncharacteristically well-defined finger in the Louvre portrait of John the Baptist – which seems to go against Leonardo’s career-long insistence on the need to avoid sharp boundaries and his attempts to perfect the sfumato technique – was in fact intentional rather than the product of a misguided restoration, as is usually claimed. Even if such assertions are not always convincing, Isaacson’s book is so beautifully produced, with dozens of high-quality colour illustrations inserted at exactly the right points in the text, that curious readers will always be able to follow his reasoning and – if they are as brave as him – form their own judgements.

But the catalogue format also has its defects, especially in the case of someone with as wide a range of interests as the hyperactive Leonardo. Most importantly, it means that Isaacson’s historical explanations often do not extend far beyond breathless enthusiasm for Leonardo’s ‘brilliance’ and assertions of his superiority to all his predecessors and contemporaries. This is the case with his treatment of both Leonardo’s art and his science. Take, for example, his discussion of Leonardo’s first Florentine period, stretching from his apprenticeship in the workshop of the established painter and sculptor Andrea del Verrocchio in 1466 to his move to Milan in 1482. Isaacson analyses well what we know of the relationship with Verrocchio and the works that Leonardo produced in this period, including a remarkable drawing of the Arno landscape from 1473 (possibly the first dated landscape in Western art), the flawed Annunciation (in which Mary has a strangely long right arm) and the unfinished Adoration of the Magi. But beyond a tiny section on Brunelleschi and Alberti, there is almost nothing on the wider context. Of course, one would not expect a full history of Renaissance art. But one would expect something about Giotto and Masaccio, whom Leonardo considered as the artistic revolutionaries who ‘showed by perfect works how those who take for their guide anything other than nature … exhaust themselves in vain’. And yet both go unmentioned.

This may be because Isaacson or his editors felt it would detract from the central focus of the book. But I get the sense that it is because Isaacson, as he admits towards the end, believes in transhistorical genius. Leonardo, he says, ‘was a genius, one of the few people in history who indisputably deserved – or, to be more precise, earned – that appellation’. The effect of such relentless, decontextualised praise is to obscure Leonardo’s very real innovations, such as the hyperdynamic method of sketching that he developed in the 1470s.

If this is the case for Isaacson’s discussion of the art, it is doubly so for the treatment of Leonardo’s science, which increasingly took up his time after his move to Milan through to the end of his life. Isaacson’s rhetorical technique here is to announce incessantly that Leonardo ‘foreshadowed’ the discoveries of the scientific giants of the 17th century, Galileo, Huygens and Newton. Moreover, he accepts uncritically the idea that Leonardo disdained book learning in favour solely of direct experience. But while it is true that Leonardo’s limited knowledge of Latin prevented him from keeping up with the mainstream of contemporary science, many of his ideas engaged with and built on those of his late-medieval predecessors. Again, to take only one example, Leonardo’s theories about impetus were not ‘proto-Newtonian’ (except in the widest sense), but were thought out within a medieval framework developed by Jean Buridan and then transmitted to Leonardo by Italians such as Blasius of Parma. In fact, Leonardo was both a weaker mathematician than these men and also somewhat more conservative than they were. He continued to countenance Aristotle’s theory of ‘antiperistasis’ (which explained the continued movement of a thrown object by claiming that the air it displaced then snapped back into place behind it and propelled it forward), despite its rejection by the medieval impetus theorists. Had Isaacson noted this, it would have placed into much sharper relief those areas of science in which Leonardo really did break new ground, such as his discovery of the workings of the aortic valve in the heart. As for Leonardo’s scientifically erroneous depiction of the glass orb in the newly famous Salvator Mundi, Isaacson’s explanation – ‘I suspect that he knew full well how an object seen through a crystal orb would appear distorted, but he chose not to paint it that way … because he was subtly trying to impart a miraculous quality to Christ and his orb’ – screams of special pleading.

A slightly cringe-inducing final chapter, which begins with an Apple advertisement written by Steve Jobs (‘The people who are crazy enough to think they can change the world are the ones who do’), consists of a set of corporate self-help aphorisms, pointing to the ways we can supposedly ‘learn from Leonardo’: ‘Retain a childlike sense of wonder’, ‘Be open to mystery’ and so on. It would be profoundly unfair to judge the rest of Isaacson’s passionate book on the basis of this section, but it does point to its central weakness. I have read that Leonardo: The Biography has already been snapped up in a ‘seven-figure bidding war’ by Paramount, who intend to produce a biopic starring Leonardo DiCaprio (himself apparently named after the artist). This is appropriate, for there is something of the Hollywood blockbuster in Isaacson’s beautiful, meticulously produced and unsubtle book. Those who might want something a little less dazzling and showy, but a little more historically sensitive and – for want of a better word – a little more European, are recommended to turn to Martin Kemp’s classic Leonardo da Vinci: The Marvellous Works of Nature and Man, first published in 1981 and updated in 2006.