MUNDANE MYSTERIES: What Is A “Gift Horse”, and Why Shouldn’t You Look In Its Mouth?

Like many old proverbs, “Never look a gift horse in the mouth” used to have a very literal meaning before the passage of time turned it into a figure of speech. Not looking a gift horse in the mouth means being thankful for a gift, even if you secretly wished for something else.

The phrase originated long before the invention of cars, when horses were widely used for work and transportation. The first appearance of this particular proverb is often traced back to A Dialogue: Of the Effectual Proverbs in the English Tongue, published in 1546 by London’s John Heywood, where he argues that “No man ought to look a given horse in the mouth.” But the phrase appears to be much older, with etymologists pointing to Saint Jerome of Stridon, an early Catholic priest who, in his 400 AD commentary on the Bible’s book of Ephesians, wrote, “Noli equi dentes inspicere donati,” which translates to “Never inspect the teeth of a given horse.”

But why a horse? And, more specifically, why its mouth? As any modern-day equestrian could tell you, a horse’s teeth betray its age. You see, horses have two sets of teeth, baby teeth & adult teeth. The older a horse gets, the more its adult teeth elongate & project outward (which is also where we get another equine idiom, “Long in the tooth”). When people needed horses every day, a horse’s value was based on his age. So, if you were going to buy a horse, you’d want to know its age before offering a price. However, if someone offered you a horse for free, it was considered rude to look into its mouth & inspect its age, just as it is considered improper nowadays when you look up your Christmas gift’s price tag on Amazon.

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