Why Shouldn't You "look A Gift Horse In The Mouth"�?

This saying dates back to the Middle Ages and exists in other languages too. It is based on the idea that, in order to find out about a horse's age and general health, you need to look at its teeth (it was, and sometimes still is, a practice to lie about a horse's age, so prospective buyers usually took a good look in its mouth.) However, if someone is giving you a horse for free, there is no point worrying about what condition it's in. since you are hardly going to refuse a free gift.

In the same way, when you get a bit of good luck or an unexpected windfall, you shouldn't quibble too much about the details – just accept it and be grateful. An example might be if someone gives you their old (but still serviceable) car – you wouldn't start poking around under the bonnet and trying to decide whether it's worth taking; you'd just take it.