The Literary Works of Leonardo da Vinci

"It is a tough one but let’s do three passages from the Richter book. One is the letter Leonardo wrote to Ludovico Sforza – Ludovico il Moro, the ruler of Milan – and he’s selling his services. This is a draft letter, it presumably went in a fairer copy to Ludovico, but he details all the military things he can do. He can build bridges for crossing moats and he can dig tunnels and he can construct weapons the sort of which are outside the common usage, as he puts it. It gives an idea of this slightly crazy ambition that he has. At the end, he says by the way, also in sculpture and painting, I can do things as well as anyone else can and will be happy to do the equestrian memorial – the rider on the horse – for your father which I happen to know you want doing . That’s a flavour of the man who was insanely ambitious, very willing to promote himself and recognised he was special. But it’s endearing, this sheer enthusiasm of listing all the different things that he can do, as though he can’t get it out fast enough. The second one would be something from the “Paragone” – the comparison between the arts. This was a set piece debate he indulged in at the court of Ludovico il Moro in Milan. It was a kind of courtly knockabout dispute between poets, musicians, sculptors, painters, and writers more generally. And he was very rude about poetry. It was a serious challenge: they were challenging for the attention of the duke, challenging for prestige in the court, and they were challenging for salaries. And Leonardo is determined to give poetry a tough time. He parades these arguments – some of them really pretty tenuous – and ultimately comes down to the assertion that the ear is not as good as the eye. The eye is the great vehicle through which we see the world and it’s the primary sense. He then assigns a descriptive role to poetry and says that poetry cannot describe a battle as well as a painting can. Which if taken as a visual description, is undebatable. But is poetry really about visual description? So, that gives you a sense of Leonardo in a court: very brilliant, very agile, and willing to bend the evidence rather creatively in his direction and to his advantage. The other passage would be one of the later writings ‘On the Eye’ from Manuscript D which is the in the Institute de France. I’m not going to give you a specific passage – they are quite a number of them – and the Richter volumes have very brilliant indices, so you can go and see where the Manuscript D Dell’occhio (‘On the Eye’) is. That is relatively well into his career, it is around 1507-1508, and he was to die in 1519. It deals with the complexities of seeing. There is geometry out there, and he is in thrall to geometry. Mathematics , but above all geometry, is the key to understanding the universe, much like Galileo said “the book of nature is written in mathematics”. For Leonardo, it is written primarily in geometry. So, there’s enormous attention to working out the reflection, refraction, aerial perspectives of objects, and how the atmosphere works and so on. But he says, and this is relatively later in his life, that we have to understand how the eye works in how we see things. The eye, he observes, is optically a very complicated instrument. He doesn’t have a focussing lens which limits what he can accomplish with his explanation. Before Kepler in the early 17th century, there’s no sense of the lens as an active focussing device. So, he tries to work out how the components of the eye – the humours as they were called: the aqueous humour, the liquid stuff, and the crystalline humour or more gelatinous stuff like the lens in particular – how these combine to create the optics to get an image. Support Five Books Five Books interviews are expensive to produce. If you're enjoying this interview, please support us by donating a small amount . His conclusion is that we can see things more or less definitely, if we put them at the right position in relation to our eye, but he says that we never see the true edge of any body. So, in a way, the geometry produces an indefiniteness – an uncertainty – and he knows, for instance, that if we’re inside a building it looks perfectly light inside but if you go outside the building you can’t see inside because it’s too dark. Leonardo is interested in the role played by our perceptual apparatus. This is very remarkable because he’s then applying that to our systems of knowledge and saying that we really need to know not just what’s out there and what we think we’re seeing, but we need to know how we’re seeing it."