Ghost of a flea

There's an ad for Volkswagen being shown in cinemas at the moment. A good-looking man is driving an elegant car; in the background the soundtrack plays a song saying: 'With positive thinking, life won't let you down.'

Harmless enough, you may think, but what makes the advertisement suddenly sickening is when the car passes a load of sheep on their way to the abattoir - they are all nodding their heads cheerfully in time to the music.

Yes, I know it's a joke, but there is still the implication that if you look on the bright side you, too, will be able to have a glamorous VW like the man in the ad, and, even if you're on your way to be slaughtered, a positive mind-set will make that jolly, too.

It won't. Indeed, this pre-occupation with thinking positively, with self-esteem and with the conviction that our thoughts somehow shape our futures is actually a dangerous obsession that leads not to happiness and fulfilment but rather disappointment and failure.