"Good and bad coin cannot circulate together."

Economists know this as the rationale for "Gresham's Law," a reference to Sir Thomas Gresham, the 16th-century financier and founder of the Royal Exchange in London, from which British commerce ruled the world for 300 years.

Gresham wrote to Elizabeth I, on the occasion of her ascension to the throne of England in 1558, that when two kinds of currency were available, people naturally would hoard silver and gold while the debased currency stayed in circulation.

This, Gresham told the queen, explained the "unexampled state of badness" that enveloped England's currency. Gresham's Law says, in short, that bad money drives out good.

What is fascinating is how frequently Gresham's Law applies to matters other than currency. Foodies say bad food has made good food harder to find. Manufacturers say shabby knock-offs of their products destroy their markets. Quality television long ago lost the war to sitcoms and car chases.

In this business — the media business — so-called "down-market" newspapers have greater readership than serious ones, what the British call "the quality press." Dancing cats are better business than GAO reports.

Last week, Gresham's Law was vividly displayed in this business. The Washington Post published a three-part series called "Top Secret America," the fruits of two years' labor by Dana Priest and William M. Arkin, two of the nation's top national security journalists.

It disclosed, in voluminous detail, how the U.S. intelligence system has exploded — at least in size, if not in effectiveness — since the terrorist attacks of Sept. 11, 2001. The nation now spends $75 billion a year on intelligence. More than 850,000 people hold "top-secret" clearances. Some 263 intelligence agencies have been created or organized since 9/11.

Nobody — not the CIA director or the secretary of defense or the nominee for director of national intelligence — knows what all of these agencies do. A lot of times the agencies don't share information with one another. Had they done so, the Fort Hood attack last November and the Christmas Day airliner bombing attempt could have been prevented. Often, employees of these agencies write reports on the same things; often the reports never are read.

Much of the nation's intelligence work has been outsourced to private contractors, who employ about a third of those who hold "top-secret" clearances. Their business is booming, but what America is getting for its $75 billion a year is not entirely clear to anyone.

Important story? You bet. But how much did you hear about it? We're guessing not much. The great Andrew Breitbart-Shirley Sherrod-Tom Vilsack-Barack Obama-Fox News-NAACP frightfest drove it out of the news.

An ideologue with a blog (Mr. Breibart) trashed the reputation of an obscure Department of Agriculture employee (Ms. Sherrod), who was condemned by the NAACP and fired by a weak-kneed agriculture secretary (Mr. Vilsack) who worried that mouth foam from Fox News commentators would stick to the president.

So much blame, so little time.

Ms. Sherrod seems to be enjoying her 15 minutes of fame, and who can begrudge her? Mr. Obama called to apologize, Mr. Vilsack offered her a better job, and the Fox News guys got a nice clean shot at the administration for bungling the whole deal.

This is what passes for news. This is the debased currency of civil discourse. "Unexampled state of badness," indeed.