I’m convinced the single best thing a man can do for his children is to find and love a woman who is a natural mother.

It’s an added bonus if the woman also happens to be a nurse. I can’t calculate the medical expenses we’ve saved over our half century of being married with three children because I married an R.N. Even today, children and grandchildren call for a consult. The fee isn’t much, just pure love, which is a better deal than most health care policies offer.

I wasn’t looking ahead to kids or parenting back in 1966 when Nancy and I got engaged. I just wanted to spend my life with the young woman. When we had our first child, I realized I knew nothing about being a dad. I figured I was in trouble. I figured our newborn daughter was in even more trouble. But Nancy figured she’d just, you know, be a mother to the tiny girl.

I fumbled with diapers and burp cloths and bottles of warm milk, terrified that I’d crush the life out of our little girl. Nancy just did what mothers do. I watched in awe. It looked natural to her, as easy as breathing in and breathing out. Somewhere I read that babies don’t come with a manual. They come with a mother. That has been true in our family. Sure, we consulted Benjamin Spock, the doctor who wrote “The Common Sense Book of Baby and Child Care.’’ Everyone used to. But natural moms like Nancy read the advice, use what made sense and forge their own path when the book didn’t seem best for the kids.

I can’t remember where this quote about motherhood first appeared, but I’ve always liked it. And on Mother’s Day, it is worth repeating: “It’s not easy being a mother. If it were, fathers would do it.’’ As a father, maybe I should be offended. I’ve done my share, after all. I’ve pitched in. But pitching in isn’t quite the same as being all in, which is how mothers I’ve known handle parenting. They don’t just contribute. They give everything for their kids.

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Here’s what a bit of online surfing told me a couple of writers have to say about mothers. “A mother is the one who fills your heart in the first place.’’ That’s attributed to Amy Tan. “Mother is the one to whom you hurry when you are troubled.’’ That’s Emily Dickinson. Both observations make a lot of sense.

Back in the days when we had a landline and our grown kids were out on their own, they’d call at regular intervals. If I could, I’d let the phone ring until Nancy picked it up. She and any of the three kids could talk effortlessly for an hour or more. It took some effort for the kids, any of them, to talk with me for more than a few minutes. I’m just not good on the telephone. After a couple of minutes of conversation with me, whichever kid was on the other end of the line would pause, clear their throat and ask, “So, uh, is mom around?’’ There you go.

“A mother understands what a child does not say,’’ I read somewhere. Our kids’ mother sure does.

She also has seemed to naturally know what each of her children has needed at any moment. She has always been on their side, and each of them has always known that. That’s why when her daughter was being left out by some mean girls in junior high, she turned to her mother first. It’s why when her older son crashed his bicycle on a steep hill near the public library, he turned to his mother to comfort him and mend the hole gouged in his cheek by the handlebar. It’s why when her younger son was carried home by a neighbor after smashing his face in a fall at the curb, the neighbor immediately gave him into the arms of his mother.

That’s why, after all these years, I’m in awe of my kids’ mother and all the other great mothers caring for their families every single day. Mothers are pretty amazing.