He had cast and recast over that pool in his memory. It was emptier than the flat to which he had returned in Joaquim Nabuco. Every article of clothing, every ornament and painting they had bought together, was drained of her existence. The flat reminded Vivien of a lodge in the jungle; you needed to shout and knock before a light came on. As the sun rose on Leblon, small waves broke on the sand like a cat gently rolling over a dead bird.

Astrud would have told him what to do.

The memory was choking him. He sat in a dazed paralysis. It infected his every bone. He couldn’t lift his glass without it trembling. The cold had finally got to him, it was in his marrow. Like Marvar.

The Iranian scientist wasn’t someone he had met only three times; he was an illness who had come in through the cracks, to nest.

Dyer got up from the zinc counter and went into the reeking urinal. Washing his hands, he couldn’t avoid his reflection in the mirror, with graffiti on the wall behind and a poster for an exhibition of Cézanne portraits at the Ashmolean.

The stale cast to his face. It explains Miranda’s reaction the day before. Grey stubble ashes his cheeks. His eyes are vacant. He looks like one of his street kids, like that accordionist outside the Oxfam bookshop. He feels himself vanishing.

A wave of panic swept through him, he was frightened by its force. He couldn’t keep his thoughts upright in his head. He had a moment of realising what a mental collapse was, the impossibility of making a decision.

A mathematical equation is true for ever, Marvar had said. But only if you knew the equation. If, however, you got rid of it before anyone else found out, who then would know it had existed – save for the person who had come up with the equation in the first place?

If Marvar was alive, he would be able, surely, to replicate his knowledge.

Leaving Barico’s, Dyer turned right onto St Giles. A little dog ran up to the bars of a gate and watched him pass by. He moved as if he were taking his last steps in chains, like someone about to commit a crime. His gestures were mechanical, his strength had leeched from him. But in the urinal he had reached a decision, and his face is oddly composed as he walks past the Oxfam bookshop towards Blackfriars, in the direction of the Taylorian, once again.

He had bottled out yesterday at Miranda’s. He is determined, this time, to see it through.

Chapter Thirty-six

THE OUTSIDE OF BLACKFRIARS had the look of a prison. The pavement was wider here, with benches. It was a spot favoured by Oxford’s homeless, a place for them to stretch out their legs like starfish, trip up consciences.