Don't shut the stable door after the horse has bolted
Don't look a gift horse in the mouth
What's the meaning of the phrase 'Don't shut the stable door after the horse has bolted'?
Don't waste time taking precautions when the damage has already been done.
What's the origin of the phrase 'Don't shut the stable door after the horse has bolted'?
The advice 'don't shut the stable door...' is one of the most long standing English proverbs. A form of it is found in 1390 John Gower's enormously long Middle English poem Confessio Amantis. This was published in 1390 and it may be that the proverb was in use in everyday language for some time before that:
For whan the grete Stiede Is stole, thanne he taketh hiede, And makth the stable dore fast.
It appears again in John Heywood's 1546 collection A dialogue conteinyng the nomber in effect of all the prouerbes in the englishe tongue:
To late this repentance shewd is.
Whan the stede is stolne, shut the stable durre.
For a more modern English version of the same proverb we can look to Daniel Defoe's Farther Adventures Robinson Crusoe, 1719:
It was only shutting the Stable-door after the Steed was stolen.
It's notable that many of the early citations use 'steed' rather than 'horse' or 'mare' which are more commonly used now. It's likely that is how the proverb was used in the spoken language for most of its life.
See also: the List of Proverbs.