“Idiom” descends from the Greek idioma: “a manifestation of the peculiar.” As its etymology suggests, an idiom compresses a pattern of thought specific to a people or place—a social id—into readymade form. This is why, when translated literally, an expression of ignorance in Germany (“Tomaten auf den Augen haben,” “You have tomatoes on your eyes.”) may be no more than a strange facial treatment elsewhere. When idioms retain their figurative meanings across cultures (for instance, the Portuguese “saber de coração” and English “to know by heart”), it is because of persistent language contact, like that forged through trade or politics.
The thought that counts (2¢) translates the American English idiom “and that's my two cents” into the languages of twenty-three countries with a ¹⁄₁₀₀ monetary unit, adjusting the expression to the current Travelex exchange rate.