How Leonardo Da Vinci gave us a Man for all time

So is the £3.3 billion it has cost to insure the paintings against damage. But then again, so is everything about the man’s talent – and its sheer range. This is a man whose reputation is beyond revisionism. Superlatives cling to him and stick for centuries.

In fact, if anything they seem to be growing. Take Toby Lester’s engaging study of da Vinci’s Vitruvian Man, which he confidently subtitles “the untold story of the World’s most famous drawing”. Buried deep inside the book is the revelation that before it featured in Kenneth Clark’s 1956 The Nude: A Study in Ideal Form, hardly anyone would have seen it.

And why would they? It’s not as though da Vinci’s depiction of a naked man in a circle and a square – “the guy doing naked jumping jacks” as one person described it to Lester – is drawn on any impressive scale. It’s just one sheet of paper, only marginally bigger than A4, and it’s a one-off too: it’s not one of a series of similar images, nor is it part of a visual treatise on the human body, or a preparatory illustration for a book. We don’t even know whether the man looking at us across the centuries with a slight frown is a self-portrait, although Leonardo would have been about the right age when he drew it in 1490, and all contemporary accounts say that he was a good-looking man, as Vitruvian Man certainly is.

Yet Lester’s story isn’t about the spread of Vitruvian Man’s fame in the last 50 years, to the point at which it has become a visual shorthand for human potential. Instead he reaches back, as da Vinci was trying to do when he first dipped his pen into the brown ink and applied it to paper – pencils not having been invented at the time – back to the ideals of classical Rome. Back to Vitruvius himself.

It’s a fascinating intellectual history, and it’s expertly told. Lester has got form here. His last book, The Fourth Part of the World, did a similar job for the 1507 Waldseemüller map – the world’s first to use the word “America”. Indeed, the two books are linked: the more he studied medieval maps and visions of the cosmos, the more he realised that the notion of man’s body somehow containing or describing the world was a commonplace medieval idea.

But where had that, in turn, come from? This is where the story reaches back to Vitruvius himself. A Roman army engineer who had retired by 20BC, he had the notion of writing a book about the principles on which architecture should be based. For these, he – along with his contemporaries – looked back a further four centuries to the statues of the Greek sculptor Polyclitus. Here was the male body as it ought to be, the very ideal that a contemporary man-god such as the emperor Augustus, then in the process of starting the biggest building the world had ever seen, should have his own image modelled on.

Architecture mattered, argued Vitruvius, because it could create civilisation – and unify an empire – by mirroring such harmonious principles. So it was important to define what the perfectly proportions of a human body actually were. “If a man were placed on his back with his hands and feet outspread and the point of a compass put on his navel,” he wrote, “both his fingers and his toes would be touched by the line of the circle going round him.” Try it at home. It works.

At this point, the direct intellectual link goes underground. Vitruvius, despite having written the ancient world’s only guide to architectural theory, dies in obscurity. But the classical design principles on which he had set so much store – in which the perfect circle represents the spiritual and the square the man-made – find strong echoes in medieval theology. The book itself re-emerges in the eighth century rather near our own part of the world – when Ceolfrith, the Abbot of Tyne and Wear, brings home a manuscript copy from Italy. And in about 1415, another eighth-century copy is found by an early Italian humanist in a Swiss monastery and sent back to Florence.

Let’s leave those ideas hanging in the ether and go back to an illegitimate son of a Tuscan lawyer from the town of Vinci. Leonardo’s father had obtained a post for him in Florence at the studio of the renowned sculptor Verrocchio. There, he might well have studied Cennini’s The Craftsman’s Handbook, which like Vitruvius also looked at the ideal proportions of the human body – essential for any credible depiction of, for example, Christ on the Cross. (Women’s bodies just weren’t worth studying, Cennini observed with true Renaissance sexism, “as they didn’t have any set proportion”).

It’s at this point that Lester’s book comes alive, because it is here that we start to see the world through Leonardo’s eyes. For him, painting wasn’t just painting, but an attempt to close in on the mind of God. “Describe the tongue of the woodpecker and the jaw of the crocodile,” he wrote in his notebooks. “Of the flight of the 4th kind of butterfly that consumes winged ants.” A few years later, in 1498, he is planning an anatomical treatise. This is how he writes it up in his notebooks: “Represent where catarrh is derived. Tears. Sneezing. Yawning. Trembling. The falling sickness. Madness. Sleep. Hunger. Sensuality. Anger, where it acts in the body. Fear, likewise. Write where the soul is… Illustrate whence comes the sperm. Whence the urine. Whence the milk. How the nourishment proceeds to distribute itself through the veins. Whence comes intoxication. Whence the vomit… Whence dreams.”

That very year, da Vinci found himself on the road from Milan to Padua with Francesco di Giorgio Martini. As Lester points out, if you’d have asked anyone at the time which of the two men would have been the more famous in 500 years’ time, the answer would have been obvious: the renowned Siennese architect, the greatest master builder since Brunelleschi. And who, about four years earlier, after years of study – his Latin was rusty and his Greek non-existent – had finally translated Vitruvius into Italian.

We don’t know what the two men talked of, whether da Vinci mentioned his plans for a book on anatomy showing us why and how we dreamed, or whether Martini told him what it was about Vitruvius that made the greatest impression on him. History isn’t kind that way. But we can guess that, as a travelling architectural consultant, Martini carried his translation of the ancient world’s only writer on architecture about with him, not least to impress his clients.

And we certainly know – though Lester doesn’t go into too much detail on the actual proof – that in 1490 Leonardo da Vinci made his drawing of Vitruvian man. Because there was, to his mind, one thing wrong with the Roman’s work: it had never been illustrated. In Roman times, it was felt that drawings would only complicate matters, that would lead different people to different conclusions in a way that words alone would not.

Yet these were different times. The human mind was in the process not just of recovering the work of the ancients but of making new discoveries. Martini’s own Treatise on Architecture, written in the 1470s was part of that new push towards completely understanding the world in science, philosophy and art. He didn’t just provide illustrations for his book, but cutaway drawings too. In Martini’s Treatise – and we know that Leonardo owned a copy – he even drew his own Vitruvian man.

The problem is, it wasn’t very good. The middle of the circle wasn’t – as Vitruvius, remember, insisted it should be – the man’s navel but his genitals. Putting the point of the compass there would be too painful for any successful experiment. And Martini’s model, somewhat effetely, doesn’t have his arms horizontal and fully extended, so it is impossible to check Vitruvius’s other assertion – that the armspan of the properly proportioned man equals their height.

Now look again at the drawing Leonardo made to prove the ancient world right. He gifts us a man who looks straight out at us, clear, serious, assured, a geometrically centred man in a box. A man for his time, our time, all time. Mostly, he’s securely locked away in an upstairs room at the Gallerie dell’Accademia in Venice. But even in our frail (compared to his) imagination, he moves.

• Da Vinci’s Ghost, by Toby Lester, Profile Books, £16.99