Economists have some hard and fast rules that—to put it mildly—don’t necessarily endear them to everyone around. For one, there’s the idea of trade-offs. It makes so much sense it’s sometime easy to forget how difficult an idea it really is.

You can’t always get what you want. But sometimes we so wished it wasn’t true. If only you try hard enough, perhaps, just maybe, there’s a way around it.

Alas, no.

That’s at least what an economist would say. Yes, your late grandmother’s den might be invaluable to you, but if someone offered you a million, a billion, a gazillion, you would tear it down in no time. There’s always a finite amount of money.

Economists don’t do infinity, at least not in this context. And they would point out that you don’t value your own life infinitely much. You cross the street by red. You eat sugar. You drive, sometimes even without a seat belt.

Now take that idea and apply it to pollution and conservation.

Choking on car exhaust is bad, but no pollution isn’t an option either. We can’t leave every stone untouched. That’s how we left the cave in the first place. Yes, Ngorongoro, Yosemite, Mozart’s birthplace, the Egyptian pyramids are all locations worth preserving.

But imagine if Unesco had been around 500 years ago. Much of Salzburg would have never been built.

If it had been around 5,000 years ago, we would have a pristine Nile delta, but no pyramids.

Had Unesco been around 50,000 years ago, we may have never made it out of the Stone Age.