In his poem “To A Mouse” Robert Burns wrote:

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 !

Quotations of this famous line gang agley more aft than perhaps any other quotation. One almost never encounters this one quoted correctly.

      - Mark