There are few happier events than becoming a grandmother, and almost none that says quite so loudly "over the hill."
Ageism mixed with sexism is a toxic brew, but somehow tolerated. It's a joke, but not a funny one, that women age in dog years, which means that no male candidate will ever be as old as Hillary is now at 462.
The issue of age has come up with male candidates (and most are men). In 2008, a Gallup poll found that 23 percent of Americans believed that John McCain's age - he would be 72 on Inauguration Day 2009 - would make him a less effective president. In response, McCain lowered the median age of the ticket to 58 by choosing Sarah Palin, 44, as his running mate.
Ronald Reagan turned his age into a laughing matter (he was almost 70 on Inauguration Day 1981), batting back a question with a quip about not using his opponent's youth and inexperience against him. He so successfully finessed the issue that no one knew the chuckle and cocked head were masking the early stages of Alzheimer's.
Given that all the Republicans' obvious 2016 contenders are young and male, ageism and sexism are safe, if unfair, lines of attack for the party. Among its potential candidates are two fresh-faced wacko birds - McCain's description, not mine - Sen. Rand Paul of Kentucky, 51, the pouty, curly-haired elf, who calls himself part of the Facebook Generation; and Sen. Ted Cruz of Texas, a 42-year-old with the chiseled features of a hawk. Then there's Florida Sen. Marco Rubio, who looks even younger than his 43 years, and the boyish Rep. Paul Ryan of Wisconsin, 44. New Jersey Gov. Chris Christie looks his age (51), but probably not for long. The camera adds 10 years and 10 pounds to a physique that doesn't need it. He didn't have his stomach stapled just for health reasons.
Hillary has weighed in on what being a woman adds to the rigors of campaigning. Hair (gray is distinguished on men; on women, not so much), makeup and averting wardrobe malfunctions require rising at least an hour earlier than a male candidate. Just last week, she remarked that the scrutiny of public life can be "dehumanizing and isolating." She hasn't seen anything yet.
What's most interesting to contemplate is the effect becoming a grandmother will have on Hillary's ambition. It's one of life's unfairnesses that a woman's peak career years often coincide with her peak childbearing years. Flextime and other efforts try to compensate for that, but no legislation is ever going to make a day longer than 24 hours or allow a mother to be in two places at once.
We may find out if a grandchild can impinge on a grandmother's peak presidential campaign years. Like children, grandchildren don't wait for you to be there to roll over, sit up, smile and say your name. Hillary's first stint in the White House provided time with family because the family lived above the store. No such luck with a grandchild. You have to go to them.
And maybe Hillary can have it both ways. She might be able to campaign, govern, attend the Group of 8 and be kept up all night by exploding Ukraines and still be able to zip off to read "The Little Engine That Could" to a grandchild.
But even bionic Hillary will realize that age mixed with a generational shift is a vivid reminder that our years on earth are finite. Hillary and her husband have both glimpsed the Grim Reaper from hospital beds. She may think twice about how best to spend those dwindling years: at a chicken fry in Iowa and working rope lines in New Hampshire or dandling Chelsea's new baby on her knee.
The Clintons have signaled how aware they are of the torch passing to a new generation. Chelsea is now a principal in their enterprises. Hillary said "grandmother-to-be" is her most exciting title yet. Bill Clinton said that Hillary wanted to be a grandmother more than she wanted to be president.