The secret to happiness in almost any relationship is knowing what not to say. Ask your new love about her old loves and you'll learn more than you want to know, and hear things you'll never be able to unhear.
Start telling your teacher that your dog ate your homework while your grandma was being rushed to the hospital, and he'll have even less patience with you than if you just say: "I blew it."
One reason we're advised to send only brief emails is that too much information gives the person at the other end much more to misinterpret - or to start chewing over at 3am. The other is that if you send a long message, the person you're writing to may feel compelled to send an equally long one back, and then it's you who's twisting and turning on what she meant by that "and" and why she never mentioned Steve. Or why she never wrote back at all.
We have, of course, been aware of this danger since the beginning of time, and yet we've never been in a position to devour (or deliver) as much information as we are today, in the age of 24/7 news cycles and social media. We've never been so tempted, therefore, to forget that the pool of knowledge is limited; it's the pool of ignorance, speculation and misunderstanding that is infinite.
As we look back on our season of surprises - from Bob Dylan's Nobel Prize to Donald Trump's election - what we're being reminded of, surely, is how very little we know. On Nov 7 (the eve of the US presidential election), thanks to more data than had ever been collected before, updated every second for 16 months or more, we all knew what was coming. By midnight the following day, we realised that all the data in the world doesn't add up to real life.
Remember in Othello how the seasoned warrior is coaxed away from the realm of knowledge and into the adjacent territories of inference and rumour by his old friend Iago? The minute he is severed from real life, on the "rack" of his own thoughts, declaring "Iago is most honest" after Iago has confided to us, "I am not what I am", the noble Moor can't be sure of a thing. Our pollsters, our pundits, our sources of "news" - our know-it-all selves - work much the same ground, though perhaps with less malicious intent, to persuade us that hearsay + opinion + guesswork = truth.
I recently got a crash course in this reality - don't we all nowadays, on dates or job interviews, on simple social occasions? - when I visited a campus. I was told that Professor X was going to host me for dinner, so of course I decided to check him out online, not least because I was fairly sure Professor X would do the same with me. I needed to show him I had thought about him beforehand; more than that, I had to be armed for two hours of small talk.
As soon as I Googled him, RateMyTeachers.com came up, and I learnt that my host-to-be was arrogant, ignorant, cruel and even sadistic. Each entry was more vicious than the last. Only later did I wonder whether this character assassination was a conspiracy among the few students to whom he'd given a "C". I didn't stop to think that I wouldn't necessarily trust these 19-year-olds in any other domain, least of all when their futures were at stake. I didn't bother to consider that it's usually those who are most vehemently pursuing an agenda who take the time and trouble to post reviews online.
I went into my host's house on guard - and hardly knew what to do with the kindly, courteous and really fun man who stood in front of me. He no doubt wondered why I was being so standoffish and reserved. Or maybe he'd come across reviews of me online and knew already that I'm arrogant, ignorant and cruel.
Greater access to knowledge is one of the glories of our age. Even many of our most materially deprived neighbours have the Library of Alexandria, multiplied by a factor of roughly infinity, in the palm of their hands, as no generation before ours has had.
The amount of data in our control is part of what has made our lives richer and happier than ever before.
On a trip to North Korea two years ago, after many years away, I recalled, with a shock, what it is to be in a sealed, predigital universe in which you can know only what you're permitted to know.
Walking around the Potemkin monuments of Pyongyang, I had to recall to myself that the glittery, ultramodern skyscrapers around me were often stage sets, with nothing but ghosts on many floors; the woman in the gleaming subway car who offered a friendly hello in English might well have been ordered to do so by her government, a human prop. The moment I returned to what I regard as Planet Earth, I went online, and rejoiced to come upon what felt like almost universally acknowledged truths.
But one thing that happens when we acquire too much "knowledge" is that, like Othello, we sometimes fail to distinguish it from what can never be known, which may not be untrue. Another is that we're tempted to lose sight of the distinction between those realms, like science and health, where the more data we have, the better, and others, like human relations, where the opposite may be true.
Knowledge comes to seem an end in itself, and then we gobble it down and gobble it down without stopping to realise that it's Iago - or that anonymous writer of the Wikipedia entry - who's serving it up to us, and that wisdom sometimes depends on seeing how much knowledge doesn't know and how much every day is shaped by unexpectedness.
As a boy I was aware that knowledge was the coolest form of power around; nearly every adolescent wants to be in the know. What I couldn't see was that it's precisely in matters of highest importance - love, terror, is there a God, and why is Iago possessed by the Devil? - that we're outside the domain of knowledge. That the more information we gather, on anyone from Angelina Jolie to Donald Trump, the less we seem to know. And that nobody trustworthy wishes to run for public office now, in part because, in the age of knowledge, no one is unstained before the global jury of the Internet.
Anyone reading this essay will accumulate more knowledge today than Shakespeare did in his entire lifetime. But Shakespeare knew much that it's harder for us to see. As my friends keep telling me what's going to happen during the Trump presidency, I remember everything they were telling me eight years ago about how President Obama was going to change the world. Thank heavens President Obama was wise enough sometimes to point out that none of us even knows what's going to happen tonight.
- The writer is the author, most recently, of The Man Within My Head and The Art of Stillness.