parIn his lap Gilbert held a small book. It had a black cover that was worn and scuffed and seemed to Gilbert a thousand years old. He had carried the book carefully this far, the way you carry something precious, cradling it in his hands as he walked along the streets, keeping well back from any passer-by who might brush against him and make the book fall.

parWe have found within ourselves, or we have developed, or we have been given each a fragment of mind. This was Gilbert's momentary thought.

parHe got up from the bench and walked across the park towards the station. And he turned the thought over in his mind as he went, crossing the grass and taking the path, going out by the gates and into the crowds milling around by the barriers and the ticket machines. A fragment of mind. Does that mean a fragment of the Great Mind? Or what Great Mind?

parGilbert bought some sweets at the kiosk, and then under the river he went, Embankment to Waterloo. Then the Jubilee line east, everyone on the train rapt in newspapers. Between London Bridge and Bermondsey came a scream. Gilbert looked up, but no-one heard. He clutched the book tight. He took a Rolo from the packet and put it in his mouth. And the scream came again. And again. Gilbert chewed and wondered. A horrible squealing noise was filling the carriage, like somewhere a pig was being slaughtered. But no-one on the train was paying any attention. And then he thought he knew why. Under his feet the wheels were grinding on the track, the bend too tight. That's what the squealing was, he thought. That was all.

parBermondsey came and went, its station lights engulfed in black. And then the train slowed. It jerked and shuddered and somebody near Gilbert actually looked up from their book, a woman in a brown coat and a colourful scarf stared with shiny eyes at the lights in the ceiling as they flickered and dimmed as if about to go out.

parThe train lurched forward. Then it slowed. And then it stopped. The lights went out. And there was silence. And then Gilbert heard a soft swoosh, and there was a sudden draught of cold air, and he looked over his shoulder and saw in a dim light that seeped along the tunnel from the distant station that the door behind him had slid open.

parGilbert hardly dared to breathe. The Great Mind was moving in the tunnel. Or something like the Great Mind was out there. Gilbert could hear It. It was calling for Gilbert to leave the train.

parGilbert turned the little book in his hands. It was soft and warm and comforting. Above all it was real, unlike the Great Mind, which was somehow unreal, however much It seemed to be out there in the tunnel, and however much It seemed to be insisting that Gilbert get off the train. A question mark was punctuating the Great Mind's supposed existence. And yet, Gilbert pondered, how could Its existence be in any doubt, when his, Gilbert's, fragment of It was, as far as he could tell, very real? He looked at the figures sitting near him in the darkness. No-one was moving. No-one was speaking. It was as if like the train they had been brought to a complete halt, like they had all been frozen to stone.

parCome out, said the Great Mind.

parGilbert moved towards the door. It was dark out there. A great rush of cold air whistled past. The dark brickwork and grimy pipes and cables that stretched in each direction held a strange, slightly morbid, fascination. There was a strong smell of oil or something, and something that had been burnt. Or electrocuted. Gilbert looked down towards the tunnel floor. All he could see was black. But there must be something to land on, were he to jump from the train, as the train couldn't just be floating in the middle of nothingness. Or could it? Gilbert leapt down and landed with a scrunch. The book flew from his hand, and he reached out instantly and snatched it back. There was a hiss from some part of the train. Something creaked. Something groaned. And then the train moved off, silently at first and then with a loud whiney roar. Somehow Gilbert was glad to see it go. He waited until it was some way down the track before he moved along the tunnel, keeping close to the wall, holding the book tight, as the train rounded a bend up ahead with a dull roar and a sort of swooshing sound, the air in the tunnel being sucked away.

parGilbert came to a small hole, a low tunnel going off to his left.

parCome down here, said the Great Mind. Don't be afraid. I am with you.

parGilbert stared into the darkness. A faint roar had started up behind him. He looked back up the tunnel. The tracks gleamed dully in the soft dim light. Another train was coming. It would soon be racing past him, maybe sucking him under in its speed.

parGilbert seemed to have little choice but to follow where the Great Mind led. He took a tentative step down the small tunnel. It was not much taller than he, and crowded in on him, cramped and cold. Cautiously he put one foot in front of the other, making his way slowly down into the dark.