The people he stopped were always very polite to him, and would say kindly, ‘Yes, of course you cracked it: you really are amazing.’

Then he would be really happy, and spreading his arms wide like the wings of a bird, he would run along the road shouting, ‘I cracked PORPHORY, I really am amazing, I really am amazing …’ Everyone who saw him felt deeply sorry for him.

That day, I didn’t say much to Jiang Nan, but I lit his cigarette for him and sent him on his way as politely as I could. Then I asked Huang Yiyi what she had been talking to him about, and she said she had asked him how he’d found the key to PORPHORY.

I said jokingly that she should have asked me – well, it wasn’t entirely a joke; I could have told her.

She answered the question I hadn’t asked. ‘I saw you leave the carpenters’ shed – you’ve been checking up on me.’

I tried to sound convincing when I denied it, and told her that it was purely by chance that I had discovered she was making some mystery machine, and I hoped she would tell me what it was for. She then explained her domino theory. It seemed very strange to me, and I wanted to ask her more about it. She said, ‘That’s enough – I’ve already given up on it, but I do have a new idea. Last night I had a dream. In the dream I was holding a fistful of hornets, and the hornets stung my hand and then flew away, leaving all these holes. My hand looked like a sieve full of holes, and Arabic numerals came tumbling through them …’