At one's wits' end
What's the meaning of the phrase 'At his wits' end'?
Perplexed; unable to think what to do.
What's the origin of the phrase 'At his wits' end'?
From the Bible, Psalms 107:27 (King James Version):
They reel to and fro, and stagger like a drunken man, and are at their wits' end.