It was news everywhere, from CNN to “Saturday Night Live.”

The principal of a Tallahassee charter school was fired after a photograph of an iconic masterpiece, Michelangelo’s heroic nude sculpture David, symbol of one of the Bible’s best-known parables, was shown to sixth-graders.

It wasn’t the nude sculpture that proved so embarrassing. It was the behavior of grownups.

The official explanation was that parents were supposed to be told ahead of time that the picture would be shown — as they were last year — but weren’t.

“Parents are entitled to know anytime their child is being taught a controversial topic and picture,” said Barney Bishop III, chair of the board at Tallahassee Classical School, in an interview with the online magazine Slate.

That, presumably, is so they can keep their children home on those days.

The policy should concern the public. It’s a charter school, not a private one, which means taxpayers are paying for this. For their money, they’re entitled to schools that teach critical thinking, which has been called our greatest national deficit.

Critical thinking is essential to informed citizenship. But it is incompatible with a policy that allows students to avoid controversial subjects. In fact, it’s impossible under such circumstances.

The David sculpture itself is an example of the difference between visceral and critical thinking.

Some people, like those overly squeamish Tallahassee parents, see only genitals. People around the world see much more.

David’s nudity expresses the religious spirit Michelangelo was appointed to convey. Facing the giant foe Goliath armed with sword and shield, David is clad only in the invisible armor of his faith in God. He carries only a slingshot. His body is tensed for combat.

The Galleria dell’Accademia, in Florence, Italy, where the original statue stands, offers this additional explanation on its website: “Thanks to its imposing perfection, the biblical figure of David became the symbol of the liberty and freedom of the Republican ideals, showing Florence’s readiness to defend itself.”

On her blog, Florida Jolt, Delray Beach political activist and former mayoral candidate Tracy Caruso made the statue sound pornographic by describing one of the most important works of art in history as “a picture of a penis.”

Liberty and freedom are the products of centuries of controversy, which continues to this day. A school that suppresses controversy is no friend of freedom.