Were these communiqués classified? Threats to national security? Recipes for risotto or blueprints for building a hydrogen bomb? And what if anything did they reveal about the epistolary endeavors of the former secretary of state and current Democratic nominee for president? The F.B.I. had no idea when Mr. Comey made his remarkable disclosure.

This case is not about personalities. Mr. Comey is not Hoover’s ghost. Nor should it be about politics. The F.B.I. is supposed to be above that. But it is about power, its use and abuse.

Mr. Comey’s reputation for independence in the face of executive power was forged in a 2004 confrontation with President George W. Bush over the widespread and mostly secret warrantless searches of Americans’ emails. When Mr. Comey, then the acting attorney general, found out about it he confronted the president, declared the program illegal, and said he would resign if it were not altered or abolished. He later reflected that it was hard to straddle the tracks in front of a speeding railroad train and yell, “Stop!”

Sadly for many who admired his courage, Mr. Comey now more closely resembles the runaway train. His conduct calls to mind the testimony of another secretary of state, George P. Shultz, in the aftermath of the Iran-contra imbroglio — the disastrous decision by the Reagan administration to sell overpriced weapons to Iran’s Revolutionary Guards, skim off the proceeds, and slip millions to rebel cadres in Central America after Congress had cut off its support.

Mr. Shultz said, of the director of central intelligence during the Iran-contra affair, William J. Casey: “The C.I.A. and Bill Casey were as independent as a hog on ice and could be as confident as they were wrong.”

Substitute “the F.B.I. and Jim Comey” and we have a sense of where we are.

In his role as the director of the bureau, Mr. Comey is not supposed to be a Republican or a Democrat. He is supposed to stand as the living embodiment of the statue of Justice — wearing a blindfold, holding a sword in one hand, a balancing scale in the other. In light of his recent conduct, the blindfold and the sword seem intact, but the scale seems to have gone missing. America could use the balance.