(Neko ni koban; “Gold coins to a cat”)
Casting pearls before swine. No matter how valuable or useful something is, if you give it to someone who doesn’t understand its worth or use, then it won’t do them any good.
This brief phrase strongly implies a verb, and most likely is the condensed form of a longer phrase, even a complete sentence. But for now we’re left with two nouns and a particle.
The first noun is 猫 (neko), “cat.” The second, 小判 (koban), is an old form of currency: an ovoid coin (gold, in theory, but as with many examples of gold coinage the currency was increasingly debased over time) used during the Edo period. The particle between them is に (ni), which has myriad uses, generally positional or directional in some way. You can see above that “to” is a good translation in this case, although “for” would work just as well.
It turns out that there is a longer version: 猫の前に小判 (neko no mae ni koban), “gold coins in front of a cat.” Note that this changes our interpretation and translation of the particle に from directional to positional, although the saying’s meaning is the same and we’re still lacking the verb that would make it into a proper sentence. An alternate version of the shorter phrase simply replaces 猫 with 犬 (inu, “dog”). In fact, it seems there’s a whole series of similar sayings revolving around the futility of giving something valuable – especially Buddhist signs or teachings – to any of a number of animal species.
This kotowaza is also from the Kyoto Iroha karuta set.
One of Japan’s more visible, if unremarked-on, cultural oddities is the 招き猫 (maneki-neko), a statue of a beckoning cat. The maneki-neko is said to bring good luck, or money, and can often be seen in Japanese businesses, on the counter or by the door. (In the US, the practice has spread for some reason to shops and restaurants in any East-Asia-related business.) In one of life’s little ironies, the maneki-neko is often portrayed as carrying a koban coin. Presumably this is not because the cat itself finds the coin useful, but because it is delivering the gold to its master.
(“E no gu wo Keita ni yatta no? Aitsu wa zenzen aato ni kyoumi ga nai kara, neko ni koban da yo!”)
[“You gave the paints to Keita? That guy’s got zero interest in art; it’s completely wasted on him!”]