Lead on, MacDuff
The origin of this phrase is the Shakespearean play Macbeth. In actuality, it is a misquote as Macbeth's actual line in the play is "Lay on Macduff, and damn'd be him that first cries, 'Hold, enough!'"
All the world's a stage
The origin of this phrase is the Shakespearean play As You Like It. The context of the quote is:
All the world's a stage,
And all the men and women merely players:
They have their exits and their entrances;
And one man in his time plays many parts.