wasting one's breath; preaching to deaf ears
Idiomatic expression meaning that explaining something to someone who cannot understand is pointless, like reading the Analects to a dog. Often used when advice or reasoning is ignored.
No matter how many times you tell him, it's useless. It's like casting pearls before swine.
Explaining the new proposal to that stubborn boss is just a waste of breath.
Equivalent to 'casting pearls before swine'. 犬に論語 focuses on wasted explanation, while 豚に真珠 emphasizes giving something valuable to someone who cannot appreciate it.
From the literal image of reading the Analects of Confucius (論語) to a dog (犬), implying that the dog cannot understand the content. The exact origin is uncertain, but it is a traditional Japanese idiom.