Children are brilliant and adolescents, while less so, are never wrong. Adults? There’s where problems arise. Many grown-ups are clueless but unwilling to utter the rarest words in the English language: “I don’t know.”

So, let me state for the record that I was wrong, and I didn’t know.

Such wisdom came to me, as it often does, in a sanctuary of beauty, specifically the Philadelphia Museum of Art, where I realized that I was wrong about Andrew Wyeth and knew virtually nothing about him.

The seven-decade retrospective “Memory and Magic,” which runs through July 16, inverted my view of the artist. And the wonder of the show, as is true in life, is not simply appreciating something with a fresh approach but being liberated from the shackles of bias and ignorance that hobble daily thought.

Being wrong has its virtues. No one likes being wrong for the record, in print, before an audience, in the voting booth. There’s no glory in quashing facts like roadkill or masticating arguments until they’re gruel.

But radically shifting approach, while abandoning prior notions, can deliver the same joy as eliminating dross. You immediately feel lighter for doing so. Which makes sense when you’re discarding the garbage of long-held assessments.

We’re raised with certain preconceptions. On Wyeth, mine was this: He was too popular with too many people to be much good. Why the same was not true of football or Picasso, revered in our household, was never addressed, but who says there’s logic in taste? Wyeth was calm, clear and unambiguous, the opposite of modern, and art for your aunt.

So, all these years I clung to the notion that Wyeth was a superior technician almost clinical in his execution and bereft of emotion, a realist. This is not what greets you at the Art Museum show.

There are adverse opinions about audio tours, that they tell visitors what to think, instead of letting them see. In this case, though, the aural guide is a revelation.

Art history is a unique language, one I often can’t fathom, multisyllabic gobbledygook bordering on comic relief. So when a curator says of Winter, 1946, the tempera panel of a capped boy marching down a hill, that “the hill is Wyeth’s father,” my first response, as well as my second and third, is “yeah, right.”

But then Wyeth, a half century later and almost 90, says in my ear, “The hill became a portrait of him,” speaking of his father, who died on the other side of the mound. “I spent the whole winter on the painting – it was just the one way I could free this horrible feeling that was in me – and yet there was great excitement.”

And I go, “whoa,” because I’m wrong about the whole business.

Wyeth turns out to be an intensely emotional artist, a symbolist more than a realist, and what’s not there – and the show tells you what isn’t, especially in the exquisitely documented Groundhog Day – is as important as what is. Spring Fed, a 1967 work seemingly depicting a stone trough, is about the death of Wyeth’s childhood hero, Robin Hood. Whoa, again.

Six years ago, my father went to the mammoth Norman Rockwell exhibition and had a similar response, abandoning ancient assumptions. I remember how exuberant he was about seeing something in a new light, the freedom that comes in realizing you might have been wrong.

It’s not always possible to be moved. Last year’s Dali show failed to budge me one bit.

But the Wyeth show taught me I was wrong, and I didn’t know, opening my eyes to seeing more, not only what’s there but also what isn’t.

Karen Heller is a columnist for Philadelphia Inquirer. Readers may write to her at the Philadelphia Inquirer, P.O. Box 8263, Philadelphia, Pa. 19101, or send e-mail to kheller@phillynews.com.