疾風に勁草を知る
(Shippuu ni keisou wo shiru;
“In strong wind one learns of the strong grasses”)

Definition:

It is only after personally encountering hardships or trials that one truly understands the character and value of people who have already withstood those hardships and is able to distinguish them from people who can’t. A lot of things look easy until you have to do them. Make sure to appreciate the things that people do or endure. “Don’t judge someone until you’ve walked a mile in their shoes.”

Breakdown:

We begin with compound noun 疾風 (shippuu), a fast/strong wind. This is followed by the location particle に (ni), which in this case marks the strong wind as a point in time; we can imagine an elided ～の時 (~no toki, “when”) in between the noun and the particle.

The second clause begins with noun 勁草 (keisou), literally “strong grass,” that is, grass that stands up well against wind and weather. This is marked by particle を (wo) as the object of the verb 知る (shiru), “to know.”

Notes:

This saying comes to us from our friend, the Book of the Later Han (後漢書, in Japanese Gokanjo). The story is that when emperor Guangwu of Han (光武帝, Koubutei) first raised an army and went to war, things went poorly and his retainers deserted him until only Wang Ba (王覇, Ou Ha) remained; this proverb comes from the emperor’s praise for his most steadfast commander.

The proverb is also expressed, albeit rarely, as the four-character compound 疾風勁草 (shi-.ppuu.kei.sou). 勁草 may be used on its own as a metaphor for a person of unwavering beliefs or ideology.

Example sentence:

「台風直撃の初体験で感じた恐怖から、小さい島に住む人々のことを考えて、言葉の通りの疾風に勁草を知ったような気がした」

(“Taifuu chokugeki no hatsutaiken de kanjita kyoufu kara, chiisai shima ni sumu hitobito no koto wo kangaete, kotoba no toori no shippuu ni keisou wo shitta you na ki ga shita.”)

[“After the terror of my first experience of a direct hit from a typhoon, I thought of the people who live on small islands, and felt that a literal strong wind had taught me how strong the grass is.”]