When I was in grade school, I was taught, like we all were, that previous to Marco Polo, European geographers speculated that the world was flat. Explorers in ships should beware. They might sail right over the edge.

In my mind then was an image of a vast, blue, tabletop sea suspended in a paler blue sky, little ships bobbling along, cartoon sails fat with fulsome breezes, intrepid captains squinting, unseeing, through their spyglasses. The first ship in this picture tipped into the void, a heavily scribbled blackness way below. The other ships are unable to stop or turn.

Did I choose to imagine myself a sailor on one of the ships? Did I hear the faint “uh-ohs” of dismay rise up from the tiny ships, the fainter screams?

I don’t recall ever imagining myself a doomed sailor on one of the ships. I remember childish scorn for the plight of the benighted sailors and their naive worldview. Even as we knew that the explorers were courageous, that we should show some respect for their venturing to the brink, we pitied them for the poverty of their knowledge. Certainly, a bunch of 20th-century 9-year-olds had more sense!

We knew that the world was round. We knew about gravity. We knew that neither ship nor sailor could sail off the world’s edge – even by choice. We knew about progress. We knew we were superior to our ancestors. We didn’t stand on their shoulders. We couldn’t. They were un-evolved miniatures of a sub-species.

We were giants of the future. All 40 of us, crowded like sheep in a ship’s hold, in our third-grade classroom in Cincinnati with our exhausted captain Mrs. Miller – we all knew we were superior. Ha, ha, we laughed. A flat earth!

Well, because we are smart today, and because the world is round, we know that what goes around comes around. And it is gradually dawning on us that Western culture’s entire “civilized” enterprise has been predicated on the assumption of a flat earth. Just as we could sail to the New World without falling over the edge, remove a few Indians, cut down the forests, clear farms, build roads, cities & towns, make landfills, then move west and do it again, we have lived as though we could do this forever. Forever land on a new continent rich with lumber, coal & iron, cut it, mine it, sell it for a profit, make a mess, move on. If the supply dwindles, take somebody else’s. The road of prosperity, profit and progress forever unwinding ahead of us. A flat earth, indeed, but even better, thank God! one with no edge, inexhaustible. A bottle of fine wine with no bottom, a pizza that magically regenerates its missing wedges. Full stomachs, full wallets, satisfied belches. This visionary Mother Nature keeps growing grass and trees, always hides her treasures where we can find them, and cleans up after us with unconditional indulgence for her sloppy children.

Fueled and stupefied by the zeal of our ever expansive consumption, we have failed to learn what it really means that the world is round, that the round earth is a closed spherical aquarium, with only so much clean water, so much clean air, so much oil, and arable soil, so many precious metals, so much tolerance for pollution. We have failed to learn that all living plants, animals, and resources are equal partners.

Imagine us again as smug 9-year-olds. Who is laughing now? Global warming, species extinctions, peak oil, every one of us poisoned with toxic by-products, imperial resource wars raging, fundamentalists calling down the wrath of god, or using god to justify their wrath. Imagine 9-year-olds of the 22nd century, if they have survived at all, being taught to scorn the arrogant self-indulgence of our era, our penchant for calling self-destruction prosperity and progress. The teacher might compare the flat earth fears of the 14th-century geographers to the flat earth appetites of the 20th, call it the era of the armor-plated backhoe. The kids laugh

But, we say, “uh-oh.”

We say, “Maybe a third-grade education wasn’t enough.”

We say, “Now what?”

Now what? Indeed!

The first step has to be the removal of everyone in a position of power who doesn’t understand the seriousness of the situation we are in, the removal of everyone who will sell their own grandchildren for a campaign donation from Lockheed-Martin, the removal of everyone who doesn’t understand that every future decision – economic, agricultural, scientific, biological, industrial, personal, military – has to be made on the basis of sustainability. Our glorious, sick, little earth is hurtling its mad-cap way through the void and we are both the gasping patient and the emergency room doctor. If we don’t surgically remove the flat earth mini-brained microbes who think that Halliburton is Mr. Fixit and hope is to be found in war & the stock market, we are all doomed. We’re going over the edge. Flat earth, flat brain, flat line.

So, go to sleep at night chanting to yourself that the earth is round. I’m serious. A soft, sotto voce chant. It will help you sleep. Wake up in the morning promising that your every action will be shaped to that knowledge.

Otherwise, “uh-oh.”

The author lives in Brooksville and is the painter of the series “Americans Who Tell the Truth: Portraits by Robert Shetterly.”