The mind-blowing science behind how our brains shape reality ❚ All products were chosen independently by our editorial team. This guide contains affiliate links and we may receive a commission for purchases made. Please read our affiliates FAQ page to find out more. This competition is now closed The mind-blowing science behind how our brains shape reality There is a classic Monty Python sketch in which a customer, played by John Cleese, enters a pet shop to buy a cat. The dodgy shopkeeper, played by Michael Palin, whips out a terrier instead and offers to convert the dog surgically into a cat, a budgie, or a fish.