Painting Mona Lisa. Jeanne Kalogridis

rounded, like her shoulders, which inclined towards the Palazzo Medici although her face was turned towards his.

      She had always been beautiful, but now the dimness softened everything, gave her features a haunting quality they had not heretofore possessed. She seemed to melt into the air; it was impossible to tell where the shadows ended and she began. Her luminous face, her décolleté, her hands, seemed to float suspended against the dark forest of her gown and hair. Her expression was one of covert joy; her eyes held sublime secrets, her lips the hint of a complicitous smile.

      In that instant, she was more than human: she was divine.

      He reached out with his hand, half thinking it would pass through her, as if she were a phantom.

      She pulled away, and he saw, even in the greyness, the bright flare of fear in her eyes, in the parting of her lips: she had not meant to be discovered. Had he possessed a feather, he would have whisked away the deep line between her brows and resurrected the look of mystery.

      He murmured her name again, this time a question, but her gaze had already turned towards the open doorway. Leonardo followed it, and caught a glimpse of another familiar face: Giuliano’s. His body was entirely obscured by shadow; he did not see Leonardo, only the woman.

      And she saw Giuliano, and bloomed.

      In that instant, Leonardo understood and turned his cheek away, overwhelmed by bitterness, as the door closed behind them.

      He did not go to see Lorenzo that night. He went home to his little apartment and slept poorly. He stared up at the ceiling and saw the gently lucent features of the woman emerging from the blackness.

      The following morning, gazing on Giuliano in the Duomo, Leonardo dwelled on his own unhappy passion. He recalled, again and again, the painful instant when he had seen the look pass between Giuliano and the woman, when he had realized Giuliano’s heart belonged to her, and hers to him; and he cursed himself for being vulnerable to such a foolish emotion as jealousy.

      He had been so ensnared by his reverie that he had been startled by the sudden movement in front of him. A robed figure stepped forward a fraction of a second before Giuliano turned to look behind him, then released a sharp gasp.

      There followed Baroncelli’s hoarse shout. Leonardo had stared up, stricken, at the glint of the raised blade. In the space of a breath, the frightened worshipers scattered, pulling the artist backwards with the tide of bodies. He had thrashed, struggling vainly to reach Giuliano, with the thought of protecting him from further attack, but he could not even hold his ground.

      In the wild scramble, Leonardo’s view of Baroncelli’s knife entering Giuliano’s flesh had been blocked. But Leonardo had seen the final blows of Francesco’s unspeakably brutal attack – the dagger biting, again and again, into Giuliano’s flesh, just as Archbishop Salviati would, in due turn, bite into Francesco de’ Pazzi’s shoulder.

      The instant he realized what was happening, Leonardo let go of a loud shout – inarticulate, threatening, horrified – at the attackers. At last the crowd cleared; at last no one stood between him and the assassins. He had run towards them as Francesco, still shrieking, moved on. But it was too late to shelter, to protect, Giuliano’s good, innocent spirit.

      Leonardo dropped to his knees beside the fallen man. He lay half-curled on his side, his mouth still working; blood foamed at his lips and spilled from his wounds.

      Leonardo pressed his hand to the worst of them, the gaping hole in Giuliano’s chest. He could hear the frail, gurgling wheeze of the victim’s lungs as they fought to expel blood and draw in air. But Leonardo’s efforts to staunch the flow were futile.

      Each wound on the front of Giuliano’s pale green tunic released its own steady stream of blood. The streams forked then rejoined, creating a latticework over the young man’s body until at last they merged into the growing dark pool on the marble floor.

      ‘Giuliano,’ Leonardo had gasped, tears pouring down his cheeks at the sight of such suffering, at the sight of beauty so marred.

      Giuliano did not hear him. He was beyond hearing, beyond sight: his half-open eyes already stared into the next world. As Leonardo hovered over him, he retched up a volume of bright, foaming blood; his limbs twitched briefly, then his eyes widened. Thus he died.

      Now, standing in front of Lorenzo, Leonardo said nothing of Giuliano’s final suffering to Lorenzo, for such details would only fuel Lorenzo’s grief. He spoke not of Baroncelli, nor of Francesco de’ Pazzi. Instead, he spoke of a third man, one who had yet to be found.

      Leonardo recounted that he had seen, in the periphery of his vision, a robed figure step forward on Giuliano’s right, and that he believed it was this man who had delivered the first blow. As Giuliano tried to back away from Baroncelli, the figure had stood fast – pressed hard against the victim and trapped him. The unknown did not even recoil when Francesco struck out wildly with the dagger, but remained firmly in place until Francesco and Baroncelli moved on.

      Once Giuliano had died, Leonardo had glanced up and noticed the man moving quickly towards the door that led to the piazza. He must have paused at some point to look behind him, to be sure that his victim died.

      ‘Assassin!’ the artist had shouted. ‘Stop!’

      There was such outraged authority, such pure force in his voice that the conspirator had stopped in mid-stride, and glanced swiftly over his shoulder.

      Leonardo captured his image with a trained artist’s eye. The man wore the robes of a penitent – crude burlap – and his clean-shaven face was half-shadowed by a cowl. Only the lower half of his lip and his chin were visible.

      Held close to his side, his hand gripped a bloodied stiletto.

      After he had fled, Leonardo had gently rolled Giuliano’s body onto its side, and discovered the puncture – small but very deep – in his midback.

      This he relayed to Lorenzo. But he did not admit what he knew in his tortured heart: that he, Leonardo, was responsible for Giuliano’s death.

      His guilt was not irrational. It was the product of long meditation on the events that had occurred. Had he, the artist, not been so overcome by love and pain and jealousy, Giuliano might have lived.

      It was Leonardo’s habit to study crowds – faces, bodies, posture – and from this, he usually learned a great deal of information. Almost as much could be read from a man’s back as from his front. If the artist had not been absorbed by thoughts of Giuliano and the woman, he would surely have noticed the exceptional tension in the penitent’s stance, for the man had been almost directly in front of him. He might have noticed something peculiar in Baroncelli or Francesco de’ Pazzi’s demeanour as they waited beside Giuliano. He should have sensed the anxiety of the three men, and deduced that Giuliano was in great danger.

      If he had been paying attention, he would have seen the penitent surreptitiously reach for the stiletto; he would have noticed Baroncelli’s hand tensing on the hilt of his sword.

      And there would have been time for him to take a single step forwards. To reach for the penitent’s hand. To move between Giuliano and Baroncelli.

      Instead, his passion had reduced him to a witless bystander, rendered helpless by the panicked, fleeing crowd. And it had cost Giuliano his life.

      He bowed his head at the weight of the guilt, then raised it again and looked in il Magnifico‘s sorrowful, eager eyes.

      ‘I am certain this man was disguised, my lord.’

      Lorenzo was intrigued. ‘How can you possibly know that?’

      ‘His posture. Penitents indulge in self-flagellation, they wear hair shirts beneath their robes. Then slump, cringe, and move gingerly, because of the pain each time the shirt touches their skin. This man moved freely; his posture was straight and sure. But the muscles were tensed.

      ‘I believe, as well, that he was from the upper classes, given the dignity and gentility of his aspect.’

      Lorenzo’s