would come in and be terrified by the "great clay", but there was a bunch of philosophers from Helsinki University who decided they were going to infect the place with a logical system. They started making tiny balls that they put on the floor in a 20-centimetre grid. The order they imposed was in absolute contrast to this huge mass of black clay. And then there was a group of girls elsewhere in the room who were trying to make an invocation of their grandmother, who looked terrifying - very few teeth and screaming. How did the experiment progress? The thing then turned into people engaging with other people's engagement. There were these conversations between people - through objects or through the process of creating - that were totally non-verbal and about communities of affection, interest or intrigue. You could apply game theory - you could apply all kinds of social analysis to this. Were there any concerns about how people might behave? There were huge worries that people would start fucking each other or piss in the clay. We had to have two psychiatrists to make sure no one went nuts. Did people go nuts? It was absolutely extraordinary, the way that people found each other, looked after each other, but also encouraged and extended each other's experience. There was a bunch of crazy French people who took all their clothes off and started behaving in a slightly destructive way. But, actually, everybody thought they were quite funny and