At least since Shakespeare set down his Seven Ages of Man, which compares life’s progression to the acts of a play, people have tried to make sense of their lengthening lifespans by dividing them into phases. As Shakespeare would have it, one stage is for lovers, another for soldiers, and another is for judges. Finally, ‘second childishness’ awaits.

More recently, the descendants of Freud have attempted similar work. In the 1950s, psychoanalyst Erik Erikson elaborated an eight-stage model of human development, with each stage marked by a crisis and an existential question. The crises faced between the ages of 18 and 39 are concerned with finding love, and those faced between the ages of 39 and 64 are focused on making life count. People aged 65 and older are said to be looking back on their lives – with contentment or despair, but without a sense of future agency.