“We know that our high-technology society is handling our environment in a way that will be lethal for us. What we don’t know—and had better make haste to test—is whether a high-technology society can achieve a safe, durable and improving relationship with its environment.”

That statement haunts me, for it is timely—but written 50 years ago, in an extraordinary issue of Fortune magazine, a leading journal of American capitalism. Fortune’s February 1970 issue, just before the first Earth Day that April, recognized a “national movement bursting with energy, indignation and new members.” Environmentalism.

We’re 50 years out from Earth Day One now, and it’s been 42 years since we began a study of Chesapeake Bay’s systemic decline that led to today’s way-unfinished business of restoring it.

I recommend finding that old Fortune. It’s a chuckle to read the slick ads of the time: A full page, gorgeous sunset silhouetting a bathing beauty on a beach, with text, WE DIG JAMAICA. It’s an...