Sherlock Holmes again!

一を聞いて十を知る
(Ichi wo kiite juu wo shiru; “Hearing one; knowing ten”)

Definition:

Having great powers of reasoning and understanding. Learning one part and understanding the whole. Hearing just a little bit about something is enough for the person so described to realize quite a bit more. “A word to the wise is sufficient.”

Breakdown:

This sentence comprises a pair of parallel verb phrases in sequence. Each has a number (grammatically, a noun) and a verb, and connects them with the particle を (wo), marking the number as the object of the verb. In the first phrase, the noun is 一 (ichi), “one,” and in the second, it’s 十 (juu), “ten.” What one does to “one” is 聞く (kiku); “to hear,” in conjunctive form. What one does to “ten” is 知る (shiru), “to learn about,” “to be(come) aware of,” “to know,” etc.

Notes:

Some versions of this kotowaza replace 知る with 悟る (satoru), a related term with connotations of Buddhist enlightenment. Others attach the counter 事 (koto), “(abstract) thing,” to the lone numbers 一 and 十 and make 一事 and 十事.

This saying comes from the Analects of Confucius. It’s based on a longer passage in which Zi Gong is questioned and praises fellow disciple Yan Hui (apparently considered Confucius’ favorite and best disciple), saying “He hears one thing and understands ten, while I hear one thing and only understand two.” It is included in the Osaka iroha karuta set.

Example sentence:

一を聞いて十を知るくらいに理解力がある先輩に憧れて、毎日勉強にコツコツ励むことを決意した次郎であった。

(Ichi wo kiite juu wo shiru kurai ni rikairyoku ga aru senpai ni akogarete, mainichi benkyou ni kotsukotsu hagemu koto wo ketsui shita Jirou de atta.)

[Wanting to be like his senior, whose powers of reasoning allowed him to take one fact and deduce ten others, Jirou resolved to study hard every day.]