These lines are spoken by King Claudius in Act Three, Scene I of Hamlet by William Shakespeare. At this point in the play, Claudius is speaking to Rosencrantz and Guildenstern, who have been tasked with spying on Prince Hamlet to uncover the cause of his apparent madness.

In the passage:

"And can you, by no drift of circumstance,
Get from him why he puts on this confusion,
Grating so harshly all his days of quiet,
With turbulent and dangerous lunacy?"

Claudius is frustrated that Rosencrantz and Guildenstern have not been able to discover the reason for Hamlet’s strange behaviour.