Fable
Five routes laid out side by side on the review table
The Xiling caravan needed to deliver porcelain to the border town. There were three mountain routes: the north road was short but prone to rockfalls, the middle road was flat but long, and the south road required a ferry crossing. The new caravan leader was impatient and at every fork chose the one that looked fastest at the moment.
The first few trips he saved half a day. Then after a rain, he still took the north road, and a landslide ahead forced the whole caravan to turn back, with two crates of porcelain broken. The old guide said that on mountain roads you cannot look only at the single most convenient step right now; it is the next several segments linked together that make a road. The caravan leader summarized it for the first time as "the north road cannot be taken," and so on the next trip he stubbornly stuck to the middle road. But that day the middle road's bridge was broken, and the south road was the good one. He realized the problem was not any particular road, but that each step left only one choice.
The team leader switched to calculating every possible route to the end. Dozens of them were listed densely on paper, and the accountant still had not received a decision by sunset. The cargo owner grew anxious: high-value porcelain was worth more thought, but ordinary burlap should not be held up the same way.
The old guide gave him a wooden ruler: at each fork, keep a few of the currently most promising paths and set the rest aside for now; upon reaching the next stop, compare again according to the new situation. Keep too few, and you miss good paths early; keep too many, and the caravan does not move. When the wooden ruler was first used, the caravan leader kept six paths, and the accountant was slowed down again. The old guide told him to set the width according to cargo value, weather changes, and the cost of misjudgment.
On one medicinal transport, they kept three candidates. The north road was close but rain clouds pressed on the mountains, the middle road was slightly slower but stable, and word came from the south road ferry that there was a queue. At the second stop, the north road had a rockfall and the south road was clear, so they switched to the south road in time, neither charging blindly nor calculating every small path until dark. That medicinal transport showed the leader that candidate routes were not decoration. When actually moving forward, information changes; only by keeping several good routes do you have the right to revise your judgment when new information appears.
The accountant later set the scale by cargo value: ordinary goods kept only one or two candidates, valuable goods kept several, and in famine years the range was widened further. The caravan understood that prudence does not mean endless hesitation, but keeping enough good candidates at every step so that there is still room to change course in the future.