Don’t Look A Gift Horse In The Mouth

This idiom has equestrian roots; as horses teeth continue to grow throughout their lives, a good way of determining the age (and health) of the animal is by looking at its teeth. This saying therefore suggests that if you have been given something as a present, you should be grateful and appreciative and not investigate the quality or complain about the characteristics of the gift.

This idiom dates back to cerca AD 400 and was used in The Letter to the Ephesians, a Latin text of St. Jerome. The earliest English translation was seen in 1546 (“No man ought to looke a geuen hors in the mouth.” – John Haywood) and was changed to the phrase that we know and love today in 1663.