When Al Gore was a young boy on summer holidays at the family farm, he would amuse himself by hypnotising a chicken. By circling his finger around its head and making sure its eyes were following, he would immobilise the bird with fear.

“There’s a lot you can do with a hypnotised chicken,” he writes. “You can use it as a paperweight or you can use it as a doorstop and, either way, the chicken will sit there motionless, staring blankly.”