28 Jan. “To hear something straight from the horse’s mouth.” What are the origins of this English expression?

This English expression, as with many others, is a metaphor using an animal to express something which relates in no way whatsoever to horses.

Meaning

The expression is used to mean that something has been heard from an authoritative source. It generally relates to hearing it firsthand from the original source as this is the information which is the most trustworthy.

Etymology

In comparison with some English idioms which date back as far as the 15th and 16th century this expression is much more modern and dates back only to the 20th century. The earliest printed record of it comes from The Syracuse Herald newspaper in May of 1913 which reads “I got a tip yesterday, and if it wasn’t straight from the horse’s mouth it was jolly well the next thing to it.” It is suggested that the expression was first used in relation to horse racing when tips on the likely winner would be circulated around and the people who generally were the most trusted regarding this were the people who were close to the horse and knew it well; the trainers or stable workers. Therefore the idea of “from the horse’s mouth” is used to mean the advice is so solid that it is like hearing it from the horse itself. It is also suggested that it derives from the fact that trainers often lied about the age of their horse in races and that the only way to tell the age of a horse was to look in their mouth as their teeth would be a reliable indicator of their real age.

Example

An example of the usage of this expression can be found in P.G. Wodehouse’s short story in The Strand magazine which writes “The prospect of getting the true facts — straight, as it were, from the horse’s mouth — held him fascinated.”