Fable
The librarian hid the answer in the seventh book
The library in Fengling Town was very large. When townspeople asked questions, the librarian would bring over a stack of books and let them find the answers themselves. The librarian had read a lot and knew which books might be relevant. But the more books were brought over, the more readers got lost at the table.
One day an apprentice at the medicine shop asked, "Which old prescription should I look at for a night cough?" The administrator brought over ten medical books, nine of which mentioned coughs, and only the seventh recorded the subdivision of nighttime cough and cold-dampness. The apprentice flipped through them all morning and almost copied down the prescription for daytime cough.
The curator first asked the administrator to find more books, afraid of missing the answer. The table went from ten books to twenty, and the apprentice became more confused. Finding everything seemed safe, but the more irrelevant material there was, the easier it was for the real answer to be drowned out.
The second repair was to sort the books by thickness, looking at thin books first. Speed increased, but it still could not guarantee that most of the content on the desk was truly relevant. The librarian realized that the problem was not whether the answer had been carried over, but how much of the material carried over could directly help.
So the library changed its rules. After each retrieval, the librarian had to mark which pages directly supported the answer, which were merely background, and which, though they shared the same words, should not be put on the table. If most of a stack of books was useless, then even if the answer was hidden among them, it could not count as a good search.
Later, readers received less material, but it was more accurate. The curator understood that retrieval is not about piling everything possibly relevant onto the table, but about giving the reader context with as few impurities as possible; the cleaner the desk, the less easily the answer is led astray by noise.
The administrator later also retained the ability to "find everything." When encountering difficult cases, he would first expand the scope, then remove irrelevant pages, and place only the passages that could support an inference on the answer desk. Broad finding and precise placement were split into two steps, and readers were no longer intimidated by a sea of book spines.
The curator spot-checked the desk once a week: if the answer page appeared but was surrounded by nine-tenths miscellaneous books, it still had to be redone. Because the material finally handed to the reader affects judgment. Precise context is not about showing off how many books one has, but about letting useful evidence occupy the main position. Later, when the administrator trained apprentices, he did not reward the one who carried the most books, only the one who could remove irrelevant books. The reader asks for the answer, not a mountain of books. The closer the context is to the question, the steadier the later judgment. If there are too many impurities in the material, even a very clever reader later will be led astray.