An idiom meaning to waste one's words trying to explain something to someone who cannot or will not understand (literally: reading the Analects to a dog).
専門用語ばかり並べて説明しても、相手が興味なければ犬に論語だ。
If you just rattle off technical terms and the other person isn't interested, it's like talking to a wall.
彼にアートの良さを長々説明するのは犬に論語かもしれない。
Explaining the merits of art to him at length might be a waste of breath.
子どもに難しい哲学を詳しく話すのは、今は犬に論語だろう。
Talking in detail about difficult philosophy to a child is probably a pointless effort right now.