If that sounded like a rebuke of Elizabeth Warren, Bernie Sanders and some other Democratic presidential candidates, the words he uttered next confirmed as much. “The real question of leadership,” he said, “is not: Do we round up all of the good people, hope it’s more than 51 percent, come together and crush the bad people? It’s: Are we going to bring out what is better in us versus what is worse in us?”

He constantly plies this theme, which deserves constant plying. For him it’s clearly more than cant, and has roots in his stint in the military, which throws diverse Americans together, endowing them with a shared purpose.

He routinely steers clear of extremes — on health care, on guns, on environmental issues — not because he lacks conviction or courage, at least not from where I’m sitting, but because extremes aren’t where the most progress is usually made or where healing is likeliest to happen. He’s a champion of the sensible. In that way, he seems much older than his age.

But, ugh, that age. My wish for a young candidate didn’t mean a 37-year-old one. There’s much wisdom in this life that’s accrued only with the passage of years, and he’d be better off — and significantly less vulnerable in a general election — if he had even five more of them.

In 2016, I visited and spent many hours with him in South Bend, then wrote a column with the headline “The First Gay President?” I was looking at least a decade into the future, after he’d extended his résumé beyond South Bend, which has only about 100,000 people.

I’d be a lot more comfortable if there were an additional zero in that population figure, if he had a better record on race, and if there weren’t quite so many elitist mile markers on his journey to this point.

And that’s where my depression sets in. He’s so very strong but so crucially weak — which is the story of the Democratic primary, whose leading candidates are all agonizingly unsafe bets. Without a nanosecond’s pause, I’d vote for any of them over Trump. But will enough other Americans? The stakes are enormous and reassurance is elusive.