In October 1939, as Hitler, Mussolini and Stalin were plunging the world into war, an American educational reformer named Abraham Flexner published an essay in Harper’s Magazine under the marvelous title, “The Usefulness of Useless Knowledge.”

Noting the way in which the concerns of modern education increasingly turned toward worldly problems and practical vocations, Flexner made a plea for “the cultivation of curiosity” for its own sake.

“Now I sometimes wonder,” he wrote, “whether there would be sufficient opportunity for a full life if the world were emptied of some of the useless things that give it spiritual significance; in other words, whether our conception of what is useful may not have become too narrow to be adequate to the roaming and capricious possibilities of the human spirit.”

I thought of Flexner’s essay while following the New Horizons flyby of minor planet 2014 MU69, better known as Ultima Thule. This comes right on the heels of NASA’s Osiris-Rex probe entering into orbit around the asteroid Bennu, barely a month after the InSight lander touched down on Mars, and not six months since the Parker Solar Probe began its trip toward the sun.

You don’t have to be a space geek to appreciate the awe and wonder involved in these missions: New Horizons’ stunning close-ups of Pluto and its moons; the breathtaking ambition of Osiris-Rex to collect rocks and dust from Bennu’s surface and return them to earth. The marriage of disinterested science and technological wizardry on the farthest-flung adventures of the human race is what John Adams had in mind when he wrote that he had to “study Politicks and War that my sons may have the liberty to study Mathematicks and Philosophy.” It is among the greatest fulfillments of the American dream.

It is not, however, among the most commonly understood ones. Typically, we think of the American dream in materialistic terms – a well-paid job; a half-acre lot; children with better opportunities than our own. Or we think of it in political terms, as an ever-expanding domain of ever-greater freedom and equality.

But prosperity, freedom, equality for what? The deep critique of the liberal society is that it refuses on principle to supply an answer: Each of us lives in pursuit of a notion of happiness that is utterly subjective, generally acquisitive and almost inevitably out of reach – what psychologists call the “hedonic treadmill.” Religious cults and authoritarian systems work differently: Purposes are given, answers supplied, questions discouraged or forbidden, and the burdens of individual choice and moral agency largely lifted. They are dictatorships of meaning.

Flexner was acutely aware of this. “In certain large areas – Germany and Italy especially – the effort is now being made to clamp down the freedom of the human spirit,” he wrote. “Universities have been so reorganized that they have become tools of those who believe in a special political, economic, or racial creed. Now and then a thoughtless individual in one of the few democracies left in this world will even question the fundamental importance of absolutely untrammeled academic freedom.”

Flexner’s case for such untrammeled freedom isn’t that it’s a good unto itself. Freedom also produces a lot of garbage. His case is that freedom is the license the roving mind requires to go down any path it chooses. This is how fundamental discoveries are usually made. It’s also how countries attract and cultivate genius – by protecting a space of unlimited intellectual permission, regardless of outcome.

All of this, of course, has its ultimate uses – hence the “usefulness” of Flexner’s title. Newton’s third law of motion begets, after 250 years, the age of the rocket; the discovery of the double helix delivers, several decades later, Crispr. It’s also how nations gain or lose greatness. The “reorganized” universities of fascist Italy and Germany had no place for Leo Szilard, Enrico Fermi or Albert Einstein. They became the Allies’ ultimate weapon in World War II.

Which brings us back to New Horizons, Osiris-Rex, InSight and every other piece of gear flying through the heavens at taxpayer expense and piling up data atop our already vast stores of useless knowledge. What are they doing to reduce poverty? Nothing. Environmental degradation? Zippo. The opioid crisis? Still less.

And yet, in being the kind of society that does this kind of thing we also discover the highest use for useless knowledge: not that it may someday have some life-saving application on earth, though it might, but that it has a soul-saving application in the here and now, reminding us that the human race is not a slave to questions of utility alone.

There are plenty of reasons to worry about the state of the American mind today, as well as the state of the university. But let’s start 2019 on a happier note. Even in the midst of the shutdown, the New Horizons mission was still considered an “essential” activity of government. If Flexner were alive to witness it, he might say, “most essential.”

Bret Stephens is a columnist for The New York Times.