The resignation of David Petraeus as director of central intelligence ― prompted, you may have heard, by the discovery, via an email trail, of an extramarital affair that possibly posed a security risk ― leads to a cascade of concerns.

Leaving aside questions of morality, which would only lead to foolhardy and empty pronouncements, it’s fair to ask who will take the helm of the Central Intelligence Agency, which seemed to flourish under Petraeus’s leadership. What does this mean for the unending struggle against Islamic fundamentalism, the investigations into the Libyan attacks, Iran’s blossoming nuclear program, and a host of other issues crowding the agency’s plate? How did the FBI investigation that unearthed the whole thing unfold, and did the bureau overstep its boundaries while at the same time under-informing its overseers?

Perhaps most vexing of all, why oh why, decades into the popular email experience, did one of the smartest men in the country, a master of intelligence and spycraft, a leader who recast the entire Iraq strategy and who ran the agency that helped track down Osama bin Laden and oversaw large parts of what seems to have been our first cyberwar, why on earth did he think his romantic emails could remain secret?

What is it that we still don’t understand about email? Why do even people versed in encryption, worms and firewalls, people who do their reading in Scifs and have their iPads wiped clean after visiting Asia for fear of insidious Chinese computer viruses, lull themselves into believing that email is a safe place to carry on relationships or have conversations or, really, do anything they would prefer to keep secret?

Let’s state for the record a fairly basic observation: Email leaves a virtually permanent, indelible record. You can empty your trash, you can bury your laptop, you can create fake accounts, but chances are there’s a server somewhere with a twin version of your email, and it’s waiting in the shadows to come back and haunt you. Ghosts in the machine.

We should leave it to the cognitive scientists ― or the psychiatrists ― to figure out why we have so much trouble remembering this. (NIH grant alert!) But: We remember not to put the radio in the bathtub; we remember not to drink gasoline; most of the time we remember not to lick the pole on the chairlift. Yet we cannot remember that even the most deeply buried email is probably findable.

It’s easy enough to hazard a few guesses as to why, of course. In the span of human invention, email is still relatively new (compared with, say, the telephone). It’s also fast. True, maybe it’s not as fast as Twitter, instant messaging, texting and other, more recent jack-rabbit technologies that have lapped it. But email is still maybe too fast for our brains to catch up with. The message came to us in a flash, we responded quickly, therefore it will vanish ― it’s as ephemeral as the transaction.

Maybe speed also eats away at our superego. The desire to respond, to emote, can be so fierce that sometimes we do it before thinking. Unlike a letter, or a conversation, where you can change course and repair the damage, an email, once sent, can rarely be made to disappear. This can be a problem. Though we put a man on the moon, though we moved several space shuttles over bumpy roads to museums, we still haven’t managed to invent an all-powerful email recall button. It’s worth remembering, too, that those fantastic free email services many of us use are free for a reason. Data mining, pop-up ads and goodness knows what other digital strings are attached that we ignore, blinded by convenience and the right price.

David Petraeus isn’t the first to forget all this. Many of those on high have been brought low by email, romantic and otherwise. Although he did have the Federal Bureau of Investigation with its manifold resources on his tail, it’s hard to argue that the retired four-star general and intelligence chief shouldn’t have known better. After all, while Petraeus’s career was unraveling, Daniel Craig and the James Bond franchise were racking up box-office dollars with a story in which the British security apparatus is brought down by computer hacking.

We hope Petraeus, his family and all those involved in this dark and unhappy tangle find a way to heal. We also hope that the CIA weathers this moment. But it’s possible that Petraeus has presented the rest of us with what the therapeutic industrial complex calls a supremely teachable moment. Email is a fantastic tool. It’s revolutionized our world. Just don’t expect it to keep your secrets.

(Bloomberg)