Xu Guangqi
Hand Over the Needle
What you want is not the finished embroidery but the needle that made it
Xu Guangqi, 'Miscellaneous Remarks on the Elements'; Matteo Ricci, preface to the Chinese Elements
He wanted the needle, not the embroidery. This asks what to hold on to when answers come too easily.
What actually happened?
In the spring of 1607 the first six books of the Elements were finished. An old Chinese saying went: show people the embroidered mandarin ducks, but never hand over the golden needle. In his notes on the book Xu turned it round: hand over the needle for others to use, and never mind the finished ducks. This book, he added, does more than give you a needle. It teaches you to mine the ore, smelt the iron and draw the wire to make one.
Results are the ducks, reasoning is the needle
The European calendar methods gave accurate results. That was the finished embroidery. Xu wanted the reasoning that let him work them out again himself. A borrowed result fails when conditions change; with the needle you can stitch a new pattern.
A formula copied from somewhere breaks in a new setting. One you have derived, you can adapt.
What can be derived need not be guessed
He wrote that this book left nothing to doubt, guess, test or correct. Each step follows from the one before, so you can check it yourself, without trusting anyone and without relying on luck.
Sign off on a tool's conclusion only once you can trace it back step by step.
Hold the needle yourself
Ricci explained aloud and Xu wrote every sentence, which meant understanding each one well enough to put it into Chinese. They went through three drafts. Following someone else's explanation is not the same as being able to write it.
Close the tool and redo its derivation from scratch. Wherever you get stuck is what you still have to learn.
How do I use it today?
Where you are: The tool's answers are quick and right, and you are less and less able to say how they were reached.
Ask first: If one condition changed, could I work this answer out again myself?
Where it goes wrong: Reading it as 'invent everything from scratch'. Xu did not invent geometry. He took someone else's proofs and wrote them into words he could explain. The point is being able to redo it, not refusing to use it.
Lines to keep
Don't settle for the embroidered ducks. Ask for the needle.
What you can derive, you don't have to take on trust.
Write it out yourself, and the needle is in your hand.
Same situation, other people are asking
I shipped what it gave me without working through it myself.I ask it everything. I've stopped thinking.I handed it in and I can't explain it.Without the tool I can't get the first sentence down.The tool does my thinking · all 8 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.