Fable
Warehouses you can reach and warehouses you can't
Old Ma opened a woodworking shop specializing in custom furniture. The shop was fully equipped — saws, planes, chisels, squares, ink lines — each tool had a fixed place, was numbered and hung on a whole wall of tools. Old Ma spent three months making the wall neat and beautiful, with a label on every tool, even stocking three models of rivet gun, with no empty spots and no duplicates on the wall.
A new apprentice named Xiao Zhang joined the workshop. Xiao Zhang was deft, but had a problem on his first day. A customer brought in a wooden board and asked for a groove to be cut on the side. Xiao Zhang walked to the tool wall, stood there for half a minute, came back with a chisel, and forced it by hand. The groove was cut, but crooked, and a piece of wood splintered off the edge. Old Ma watched nearby without saying a word.
At the end of the day, Old Ma called Xiao Zhang over to the tool wall and pointed at an electric trimmer, saying: use this for grooving. Xiao Zhang looked down at the label on the trimmer—"Woodworking Trimming Equipment Type B"—and said: Master, I've seen this label, but I don't know what it has to do with grooving. The label shows the equipment model, not "use this for grooving."
Old Ma could not sleep that night. He had organized the tool wall himself: clear numbers, fixed positions, not one missing. But what Xiao Zhang did not recognize was not the tools—it was the connection between the name on the label and the job he had to do. The tool wall tells you what tools exist, where they are, and how to adjust them; it does not tell you which one to take for which job.
The next day, Old Ma hung a new board beside the tool wall called the "Job Index." It listed only work scenarios: "Board grooving → trimmer," "Panel joining → biscuit joiner," "Rounded edges → chamfer plane," "Tenon cutting → table saw with tenoning jig." Each row began with "what situation you encounter," and the last column pointed to the tool on the wall.
Old Ma set a new rule: for every new tool brought in, a record must be added to both walls at the same time. The left wall gets the tool number and storage location; the right wall gets at least two usage scenario descriptions and corresponding pointers. The two walls are updated in sync, and tools that are not synced are not allowed on the wall.
A month later, Xiao Zhang could already take jobs independently. A peer came to visit the workshop, saw the two walls, and asked Old Ma what the point was. Old Ma said: The left wall is the warehouse ledger—how many tools there are, where they are, and what specifications they have. The right wall is the master's experience—which job takes which tools, and which to take first and which later. A tidy warehouse does not mean the apprentice can do the work; only when both walls are complete does it count.
Later, peers copied this approach. Old Ma told his apprentice: remember, the left wall governs "what there is," and the right wall governs "how to use it." Missing a tool on the front wall is an inventory problem. Missing a scenario on the back wall means you clearly have the tool but cannot think to reach for it. These two kinds of emptiness must be accounted for separately.