The case for Joe Biden to accept the inevitable dictates of his age and not run again is persuasive. Too much rests on the health and fitness of the president to turn it into a kind of roulette: When will his number come up?

Worse, what if Biden fails mentally and stays in office incognizant of his condition? Being the president of the United States is the most demanding and most responsible job in the world.

Winston Churchill got a second term as prime minister of Great Britain in 1951, and lots of stuff went wrong, from immigration policy to the growth of unchecked union power. History’s greatest prime minister had lost his acuity.

As I am older than Biden, I can say he should quit. I love to work, but there’s the rub: Not all people and all work are created equally. What I do isn’t critical and doesn’t decide the nation’s future or war and peace.

No one would suggest that an artist toss the easel at a predetermined retirement age. Noel Coward, the great English entertainer, said, “Work is more fun than fun.” That depends on the work.

Age is a complex equation for society, and retirement is a nettlesome problem. France is in revolt over President Emmanuel Macron’s move to raise the retirement age from 62 to 64. Very reasonable, most Americans say.

The issue in France is simple: The French can’t afford huge state pensions any longer. There aren’t enough people at work to pay for those who have retired on their nearly full salaries. You can vote the population rich, but you can’t vote in new, young taxpayers to keep them rich. When the Social Security system falters in the next decade, America may be staring at the same sums as Macron.

Mandatory retirement is a crude way to manage the retirement dilemma. Some workers are genuinely unable to work into their 70s and 80s because their bodies, their minds or both are worn out. Others are at their most productive.

My father’s mind was fine, but he was a mechanic who had done everything from building steel structures to working in mines to repairing cars. His body failed around the age of 6o. He had been doing manual work since he was 13 years old, and he couldn’t bend, twist, delve, lift, climb, stretch, grab or do any of the myriad things he had done all his life to earn a living. He had to work in a school and then a shop; he loved the school but not the shop. But he had to work. That is what he did: He got up every day and went to work.

He had worked so long and so hard, primarily self-employed, that he hadn’t had time to learn leisure — to play golf, to watch ball games, to read for recreation, or even to learn how to socialize. That came with work or didn’t happen; friends were people at work.

A friend of mine, a nuclear engineer, reached mandatory retirement age and fell apart, much as my father nearly did. He, too, had no interests outside of his family and work and was lost in the post-job world.

Something of this same problem exists for people leaving the military. Their life is the military, and then, at an early age, there is no more of that life, their life.

When it comes to Biden, things are quite different.

I know the president slightly, and I like him personally. He loves the job. He has been at the peak of power for a long time. When his term ends, he should adjourn to his beach house in Delaware and write his memoirs.

Maybe someone will teach Biden how to play boules, a European form of bowls played by older people in parks. French boules aficionados would be happy to teach him the game. The French have a lot of time in retirement to perfect their play and travel to beach destinations. They would love to bring their skill to Rehoboth Beach, Delaware. Maybe I should join them.