"I go over it to work out what they meant"

The evening has a justification, and it's that you're thinking it through. Replaying the email, the tone, the look, turning it over to work out what they meant. That's analysis, and analysis is how you understand things.

Here's the trouble with it. No new information arrives during the evening. You have the two lines of the email, and you had them at ten past two. Every hour you spend on them is an hour of rearranging the same two lines, and the rearranging produces confidence without producing knowledge. By nine o'clock you're sure of what the email meant, and you have exactly as much evidence as you had at ten past two, which was two lines.

What the evening does is run the reading again and again, and each run makes it more familiar, and familiar feels like true. By the end of the evening the reading has the solidity of a memory, and you'll go into Thursday holding it as a fact about your manager rather than as a guess you made on Tuesday afternoon and then rehearsed.

There's a body of research on going over difficult experiences, and an earlier book in this series is about it. One finding I'll borrow, from Ethan Kross and colleagues in 2005, is that the difference between going over something usefully and going over it harmfully lies in the distance. Analysing an experience from a step back, as an observer might see it, tends to reduce distress, where re-immersing in it from the inside tends to increase it. The evening is immersion. It's living the email again from the receiving end. If you're going to think about it at all, the other account in chapter 19 is the step back, because it requires you to stand somewhere other than the centre.

The evening runs longest on messages, and it's worth saying why. A message has no face, no tone and no follow-up. It's the two lines of the email without even the manager's usual style to compare them to, and it arrives at a time of day when you're tired and the reading runs fastest. A message read as cool at ten o'clock is a message that gets reread until one, and every rereading is the same eleven words. If a message lands after nine and reads as cool, the most useful thing to do with it is nothing until morning, when the eleven words will usually turn out to be eleven words.

But mostly the answer to the evening is that there's only one source of new information about what the email meant, and it's the person who wrote it. Everything else is you, alone, with two lines, for four hours. Chapter 20 is about asking. Chapter 21 is about leaving it. Either is better than the evening, and both are shorter.