Loyalty is a quality that requires careful calibration. Too much can be dangerous; too little, demoralizing.

Differing conceptions of loyalty, and differing choices of where to act along the loyalty spectrum, form the thread that links two main stories of the moment: the furor over New Jersey Gov. Chris Christie (R) and the reaction to former defense secretary Robert Gates’s memoir.

The New Jersey case, I suspect, exemplifies the perils of loyalty in excess. The Gates memoir illustrates the opposite, the trust-sapping consequences of absent loyalty.

Jersey first. In his marathon news conference, Christie portrayed the manufactured traffic jam at the George Washington Bridge and its aftermath as treachery by a trusted staff. “We’re a family. . . . We tell each other the truth,” Christie said of Bridget Anne Kelly, his fired deputy chief of staff. “I am heartbroken that someone who I permitted to be in that circle of trust for the last five years betrayed my trust,” And later, “I’m a very loyal guy and I expect loyalty in return. And lying to me is not an exhibition of loyalty.”

Christie’s sense of injury and betrayal is understandable, assuming his account is accurate. Yet I expect the eventual story of the lane closures and subsequent lying will reveal that the actions of Christie’s aides were fueled not by a failure of loyalty but by its opposite — a skewed, unthinking attitude of blind devotion.

Their job, these staffers must have thought, was to serve the boss above all. Those who failed to fall in line with that plan had to be punished — hence the infamous Kelly e-mail, “Time for some traffic problems in Fort Lee.”

And hence, if I have this right, the later denials to that same boss. If loyalty demands such excesses in the service of his career, it demands as well shielding him from the truth about that conduct. Preserving his plausible deniability is service to the Christie cause.

Indeed, to read about Kelly, fired without a Christie conversation because, he said, the fact of her lies was so clear, is to understand the depth of her devotion. “Her unrequited loyalty is not wavering,” an unnamed friend told the New York Times.

The Gates memoir requires examining the concept of loyalty from the other end: In a book titled “Duty,” did the former defense secretary violate his duty of loyalty? Gates, unsurprisingly, says not. “Having worked for eight presidents, and being a historian, I felt I had a unique perspective,” he told NPR. “And these issues are with us today. These are not issues that can wait to be written about in 2017. And so that’s the reason that I decided to go forward with the book.”

There are, of course, competing loyalties at work here: to history, to the ongoing public debate, to the presidents he served. And it is admittedly ironic when journalists who live by leaks and by cajoling inside information out of administration officials then question such candor.

But it is possible both to love the leak and disdain the leaker. For an obviously thoughtful man, Gates seems resolutely unreflective about the moral implications of his actions. Writing about a White House meeting on Iran, Gates observes, “I was put off by the way the president closed the meeting. To his very closest advisers, he said, ‘For the record, and for those of you writing your memoirs, I am not making any decisions about Israel or Iran.’ . . . I was offended by his suspicion that any of us would ever write about such sensitive matters.”

Seriously? Gates was “put off” and “offended” by Obama’s “suspicion” that someone might write about . . .the meeting that Gates just wrote about?

Gates is certainly not the first former administration official to serve and tell. I admit to ambivalence about his actions — it’s valuable, not simple voyeurism, to gain insights about how this administration operates and how, as Afghanistan and Iraq threaten once again to implode, to think about those conflicts.

At the same time, I worry that the Gates example offers an especially worrisome lesson: Trust no one inside the room, but especially don’t trust the person from the opposing party. Bipartisanship in Cabinet choices is a virtue, especially when it is not the token gesture of plunking a member of the opposing party in a minor role but the true bipartisanship of placing a political rival in an important position like Defense.

Gates’ memoir is a literal cautionary tale for the next president weighing such a choice.

• Ruth Marcus writes for The Washington Post.