This proverb advises against inspecting a present too closely for flaws or questioning its worth, since doing so is rude to the person who gave it. The image is a practical one: a horse’s age and soundness can be judged by examining its teeth, which is exactly what a buyer would do before paying for one. To do the same to a horse someone has given you for nothing turns a gift into a transaction, which misses the point of it being a gift at all. The saying is now most often heard in its “don’t look a gift horse in the mouth” form, with “never” working as an equally forceful opener.
What’s the origin of the phrase ‘never look a gift horse in the mouth’?
The proverb is extremely old and was already treated as a traditional saying by the time it was first written down. St Jerome refers to it in the prologue to his commentary on the Letter to the Ephesians, written in 386 CE. He cites it in Latin, as an instruction not to inspect the teeth of a horse given as a gift, and explicitly introduces it as a common proverb rather than anything of his own invention.
The saying entered English in the early sixteenth century. Its earliest known English rendering, “A gyven hors may not be loked in the tethe”, appears in John Stanbridge’s Vulgaria, a Latin-English vocabulary and proverb collection dated to around 1510 and sometimes cited under its Latin title, the Vulgaria Stambrigi. The wording closest to today’s comes from John Heywood’s 1546 collection of proverbs, which has “No man ought to loke a geuen hors in the mouth.”
By the seventeenth century the proverb was familiar enough in English to be alluded to rather than spelled out. Samuel Butler’s 1663 mock-heroic poem Hudibras describes a character who “ne’er consider’d it, as loth / To look a Gift-horse in the mouth”, treating it as a settled figure of speech that needed no explanation. The gap between Jerome’s Latin version and its English descendants, and the fully formed shape the proverb already has in its earliest English record, point to a saying that travelled by oral tradition for a long time before being fixed in print.