Fable
There are two ways to cut meat: one by weight, one along the grain
In the town butcher shop, two apprentices learned to cut pork belly from the same master. The old master's rule was clear: each piece of pork belly counted as one portion, and the weight had to be around one jin, with an error of no more than one liang. The older apprentice, Zhang Dao, honestly followed the rule: each piece of meat went on the scale, and with the rise and fall of the knife he cut a full jin and bagged it.
Half a year later, customers began giving feedback. The meat Zhang cut had standard portions, but the tissue structure of each piece was a mess—a single portion might have half a lean piece connected to a tendon, with a small piece of cartilage embedded in the middle. The meat Liu cut had non-standard portions but clear tissue structure—within the same piece, it was either lean or fat, and the sinews were either kept intact on one slice or completely separated. The customers' comments were very direct: "Cooking Zhang's meat requires taking apart every slice again; cooking Liu's meat gives you a complete texture the moment it hits the pan."
The master called his two apprentices over, laid the same piece of pork belly on the cutting board, and asked one question: who is the meat being cut for? Zhang Dao's answer was for the guests—every portion the same weight, fair. Liu Dao's answer was also for the guests—every portion keeps the internal consistency of the same slice of meat, with intact texture. The master said both were right, but what you cut is used in different places. Braised pork needs large, even chunks, so use Zhang Dao's technique. Hot pot needs thin, uniform slices, so use Liu Dao's technique.
Zhang Dao's method was like cutting by weight: each portion weighed about the same, regardless of how the meat's grain ran—one chop and it counted as one portion. This was useful for trades needing fair portions and easy to account for. But it could cut a whole tendon in two, and the customer would only discover after cooking that the first half was in one bag and the second half in another.
Liu the Butcher's method was to follow the grain of the meat. He didn't first ask how many ounces each portion should be; instead he looked at the fat-lean boundary, the direction of the fascia and the position near the bone, finding natural break points. Cut this way, the meat had a compact texture inside, and a single slice could reveal the character of that cut. The drawback was obvious—some slices were large, some small, and with long sinews or long cuts it was hard to keep portions even.
Later the butcher shop took on new business — supplying freshly sliced hotpot meat to the city's restaurants. The master directly retired Zhang's fixed-weight cutting technique and switched entirely to Liu's grain-based cutting technique, because hotpot requires consistent grain in the slices. At the same time he set a lower bound: no slice may be thinner than a sheet of xuan paper, or it falls apart the moment it's picked up in the hotpot; and the meat can't be left uncut, or guests can't even get it into the pot.
In the end, the master set a hybrid rule for the two apprentices: first divide the large pieces according to grain, then trim each piece by approximate weight; or first rough-cut by weight, then make an extra cut where the grain breaks at the fascia. The knife and the cutting method are not an either-or choice; it depends on whether the customer wants braised, hot pot, or filling, and then decides how to combine the two rules.