An entirely natural response to perceived danger. Heightens reflexes and prepares you to defend yourself. The problem is that we construct for ourselves a very complex version of what the threat is and how the defence should manifest itself. The neurones conspire to produce a response that for most of the history of humans was simply classified as madness. “That way madness lies.” Before you know it you’re on the heath, defying the wind and rain. Round the bend: a description that originates in the deliberate placing of lunatic asylums away from populated areas. Now we have developed various ways of averting or suppressing the heath response. Some of them are old, discovered no doubt by accident when organic matter was left to liquify and ferment. Some are twentieth century inventions. The process of unlocking asylums that began in the 1950s was largely down to lithium. We continue to refine mechanisms for keeping people off the heath, or least for keeping the heath-ravers away from mainstream television. More precisely, if they put in a cameo on mainstream television it’s as standard bearers for the derailed lives that we must not inhabit. Quick costume change and a dust of refreshed makeup, and it’s a dash from the Jeremy Kyle set to a hidden camera mock-up for Panorama. “Don’t get stressed” people sometimes say. It’s not worth it. Some stuff is worth stress. Some is not. Whether you succeed in staying this side of the bend consists in riding the continuum between the two poles.