A line of the poem "To A Mouse" is often quoted: "The best laid schemes o' Mice an' Men" to mean that well-planned plans can go wrong.
But, Mousie, thou art no thy lane,
In proving foresight may be vain;
The best laid schemes o' Mice an' Men,
Gang aft agley,
An' lea'e us nought but grief an' pain,
For promis'd joy!
-- "To A Mouse" by Robert Burns
'Gang aft agley' is Scottish and means 'Often go wrong'.
More directly translated:
gang = 'to go'
aft = 'oft' (or often)
agley = 'askew, awry' (i.e. wrong, badly. 'Gley' is 'squint', so more literally would be 'off squint')
'Aft' in this context has no relation to the nautical meaning of 'aft', but is a Scottish form of 'oft'.Yet another example of documentation failure. See also: BigDesignUpFrontBut, where is the part that interests mice? Where is the part that says "Cheese is good."?