You are a go-ahead young marketing executive. A bachelor. It is Saturday morning and you are off to do your week's shopping. About to get into your car you decide to go back and check that you locked the door. By going back you miss a minute later and miss the parking space you would have found at the supermarket and are forced to park in a nearby street instead. There are parking meters in this street, but drivers are only allowed to leave their cars for thirty minutes at a time. While you are placing your ticket inside the windscreen someone calls your name. It is a friend you haven't seen for a while. The friend introduces you to a neighbour of his, to whom he has given a lift into town. Call the neighbour, Helen. You and Helen are mutually attracted, but as she's married you part company. Or you don't. Two possible scenarios present themselves.
Scenario 1: Having left the friend and Helen you go to the supermarket, fill your trolley and join a queue at the checkout - a longer queue than the one you would have joined if you'd parked in the car park instead of the street. By the time you get back to the car you find a sixty-two year old recovering alcoholic ( a traffic warden) writing a ticket. You have a go at him, ruining his day. When he gets home after work the traffic warden takes it out on his wife. His wife have been feeling very put-upon of late and her husband's cruel words are the final straw. She packs her bag and goes to stay with her sister two hundred miles away. In the weeks that follow, the lonely traffic warden starts drinking again. He takes booze to work and loses his job. One night at home, very drunk, he decides to do himself a fry-up. The frying pan catches fire, the fire spreads, the house is gutted. So is the ex-traffic warden. His widow collects on insurance and passes the rest of her life in comfort, praising his memory.
And all because you went back to check the door.
Scenario 2: Instead of saying goodbye to Helen in the street where you park your car, you go and have a coffee with her. You still get a parking ticket, but you don't mind because you really got on with her. Over the next few weeks you and Helen meet regularly. You start an affair. Helen's husband finds out and comes after you. He attacks you. Defending yourself, you lash out. He falls and crack his head open. You are arrested, tried, and sentenced to four years in prison. By the time you get out you've lost all ambition and confidence and have no job. You very nearly fall to pieces, but instead got to the island of Santorini in the Aegean, where you spend everyday walking along the beach looking for coins dropped by tourists. One day you meet an attractive American student on vacation. She thinks you have a cute accent and runs her fingers through your fat beard and offers to share her sleeping bag with you. It's not until she returns to Boston that she realises that she's pregnant. She writes to inform you of this, but by the time the letter arrives you've move to another island, so you never learn of the pregnancy. In due course she gives birth to a boy and doesn't call him after you. Time passes. The boy becomes a man. He meets a girl. They choose not to marry, but they bring three children into the world, the eldest of whom becomes an accountant, the second a roofing contractor, and the third an Elvis Presley impersonator. The youngest is also a serial killer who over a two-year period butches twelve teenage girls, who between them, in time, would have given birth to 29 children, who between them would have co-parented 68 children, who would have brought 176 children into the world. This one hundred seventy-six would have fathered or mothered 442 children altogether, two of whom - female twins - would have been the first living beings to be emailed to Alpha Centauri, opening the door to human settlement in other parts of the galaxy.
And all because you went back to check the door.