Take a drink… Whenever anyone uses ridiculous British slang (double if it’s Jim Broadbent) Whenever you hear a section of the ‘We are bound to others’ speech Whenever you hear a part of the Cloud Atlas Sextet being played Whenever you see Old Georgie on screen Whenever an actor appears in a role as a different race, gender or sexuality than their own Whenever you see a reference to a different storyline

There’s something interesting in the idea that we refer to “a train” as an independent entity, when it’s really a collective noun (a set of things formed into a line). By extension: when you board a carriage, you’re not just riding the train, you’re in the line. You’ve become the train.