I had found a bench in front of the painting – a very small painting – which I found peculiar but not particularly exhilarating, and there was nobody else about at the time. I was spending lots of time in museums, especially art museums, and one of the things I gradually became more and more aware of was a ludicrous but entirely spooky sense, which presumably no one else shared, that human beings are unwanted disturbances, that the various works hanging nakedly on walls, for instance, are desperate to evict the living, because to have to watch us plodding around them is torture, and that day it occurred to me that the same could be said for the Aeneid, doomed for eternity to be read by students, snobs and imbeciles. The painting was Piero’s Flagellation. In it, three men are gathered in the foreground, on the right side of the painting, and they are staring in different directions. To the left of them, in the background, Christ is being whipped. I read, on a plaque beside the small painting, a little bit about the use of common perspective, which Piero introduced with his treatise, Perspective in Painting. Piero had been known principally as a mathematician in his time, but now he was known mainly for his art – and this painting, the Flagellation, had been called the greatest small painting in history. After reading this, I sat down and flipped through Virgil, and a little while later Saskia sat down beside me, putting a briefcase between us. She studied the painting for about ten minutes, then ate a sandwich. Since there is a rule prohibiting food, she ate it by looking around, taking it out of the briefcase, biting into it, and placing it back into the briefcase. I found this really amusing and smiled at her. She said, I recently finished the Aeneid. Well, last year. It’s good, I said. I expected it to be very hard to read, but it’s easy. A little while later, when we were discussing the Piero, which was to return shortly to its home in a museum in Urbino – it’s probably already back there – she said that the major shift from Medieval to Renaissance art was the fact that the people in paintings were no longer representations of characters in narratives outside the painting but characters within a narrative. This meant ideas became embodied. Perspective, she said, was a crucial part of this transformation, because, among many other things, it forced the human eye to consider its subject first as a thing and less as a symbol. Before she left to return to work, and against my intention to avoid getting to know new people, we exchanged numbers. After she left I spent some more time with the Piero, as she suggested, since I had not understood what made it the greatest small painting in history, and found something really wonderful and mysterious in it, which I had entirely missed at first. After that, I went to the museum’s bookshop, which was vast, and included, at one end, a spacious and tidy internet café, and read a bit about perspective. It was unthinkably strange that something so obvious would have eluded art for so long. And when the question of it did arise, I read, a full, intricate understanding of perspective was achieved not overnight, as I would have guessed, but over a period of four hundred years. I had been born at a time when an understanding of optics was taken for granted, and when realism in art had already been born, perfected, and exhausted. It was disconcerting to think that if I had been born in the fifteenth century, or the sixteenth, I would have been incapable of understanding the physics behind artistic perspective. In the earliest art, such as Egyptian art, I read, works were constructed with vertical perspective. If someone were in front of somebody else, the artist simply placed the closer person below the person farther away. Often an object’s position on the page had to do with its thematic importance to the story the painting was telling, so that you might have minor scenes playing out at the bottom of paintings, such as a battle, with small figures, and large figures above them. At this time it was not understood that the nearness and distance of objects could be represented by size, and the first evidence that artists had begun to associate size with depth in a field didn’t emerge until late antiquity. Then, suddenly, from the early Middle Ages onward, interest in perspective vanished, and it would not re-emerge until the rule of Charlemagne and the Carolingian Renaissance. Throughout its history, at least until it became untenable as a method of inquiry, the study of perspective seemed to be, among other things, a sign that human beings believed in an intellectual destiny that was contained in the intersecting lines of reality; by studying those lines we studied that destiny. In Byzantine art, where principles of perspective were well understood, reverse perspective was often used, so that the farther away an object got, the larger it became. In this way, the vanishing point became the viewer, and, so the book I read speculated, the lines of convergence, which would have, in reverse perspective, naturally come from everywhere, represented the omnipresence of God. The breakthroughs that would take place in fifteenth-century Florence were driven by a handful of artists, all of whom were deeply influenced by each other and some of whom were profoundly influenced by the eleventh-century work of a man named al-Hasan Ibn al-Haytham, or Alhazen, who was born in the city of Basra, and composed his great work, the Book of Optics, while under house arrest in Cairo. Alhazen’s discoveries resolved the ancient dispute between the mathematicians, like Ptolemy and Euclid, and the physicists, like Aristotle, over the nature of vision and light. He also showed that vision is not merely a phenomenon of pure sensation but also of judgement, imagination and memory. In the Flagellation, the section of ceiling above Christ is filled with light. The light is miraculous: it has no source. Everything apart from that light is geometrically and optically explicable. Christ is aware of the light, but his torturers are not.