I became interested in - what would you call it? - the behavior, the psychology, perhaps - of crowds, after getting caught up, quite by accident, in a demonstration that turned into a bit of a riot. You may have seen it on the news not long ago. What interested me was, first my own reactions to the way the whole mood changed from peaceful demonstration to violence. Secondly, I wondered if everyone else was feeling the same as I was, and what that said about us and how we behave in crowds. Why is it that perfectly ordinary, respectable members of the public can start behaving in ways they wouldn't dream of doing when at home or among friends? A crowd, it seems to me, has a collective mind, each person there adds his or her mind to the collective mind, and willingly gives up all sense of judgement and responsibility. It gives you, I suppose, a feeling of freedom, of not having to be in control. It allows you the freedom, or you allow yourself the freedom to behave in ways that, if asked, you would say were against your principles, or made you feel guilty in some way - even criminal.