The Comprehensive Mirror
Worth copying, worth avoiding
Fix the selection rule first
Sima Guang, memorial on presenting the Comprehensive Mirror
One thousand three hundred and sixty-two years of events. This is about the single rule that decided what went in.
What actually happened?
He ran the compilation for nineteen years and the finished work runs to two hundred and ninety-four volumes. In the memorial presenting it he set out how he chose: cut what was long-winded, gather what was essential, take only what bears on the rise and fall of the state, on whether the people prospered or suffered, what is good enough to copy and bad enough to warn. Shenzong, naming it, called it a mirror of what has been, useful to the art of governing. One rule throughout, which is why there is almost no ornament and almost nothing kept for completeness.
Set the rule first or you never finish
Nineteen years, thirteen centuries of material: without a selection rule you can apply mechanically, the work is infinite. Take only is the condition that let the book be completed. He did not know what to write; he knew clearly what not to.
A survey with no stated exclusion rule never ends, because any new material looks worth one more look. Write down what you will not read and progress starts existing.
The rule has to admit the bad
Bad enough to warn stands beside good enough to copy. A library of successes only teaches that there is one road that works. Failures usually carry more information, because a success can be accidental in many ways and a failure's mechanism is generally clearer.
A company that records best practice and never records post-mortems teaches new people a method assembled entirely from survivors.
The rule has to be executable by someone else
The work was divided between Liu Ban, Liu Shu and Fan Zuyu, with Sima Guang over the whole. A taste that exists only in the editor's head cannot be divided. Only a rule written down and applied identically by three people will hold for nineteen years.
If the content standard lives only with the editor, quality collapses the moment the team grows. Write it as three rules another person can apply.
How do I use it today?
Where you are: there is too much material and you are hesitating over what to include.
Ask first: what is my selection rule, and can I write it as one sentence someone else could apply?
Where it goes wrong: keeping only the successes; leaving the rule in your own head, where it cannot be divided up.
Lines to keep
Cut what is long-winded; gather what is essential.
Good enough to copy, bad enough to warn.
A mirror of what has been, useful to the art of governing.
Same situation, other people are asking
I read a lot and can't recall any of it when it matters.I've done the reps and it still isn't automatic.What I learned only works in the shape I learned it.I take in everything and keep nothing. What should I be leaving out?Nothing I study stays · all 9 questions →If this one named what you are going through,
send it to someone who needs it, or keep it somewhere you will find it again.