We have all had that moment of joyous realisation: if one small thing hadn’t happened, then our lives would have been so different. If I hadn’t got that Saturday job, then I wouldn’t have learned how to… or, if I hadn’t gone out that day then I wouldn’t have met… or, if I hadn’t had that teacher, then I probably wouldn’t have been so interested in their subject at school… The consequences of our actions, however small, can delight us.