Final answer:
The subject of the question is Theme in the play 'Macbeth' by Shakespeare, where the line expresses the manipulation of truth by evil forces.
Step-by-step explanation:
The subject of the question is Theme. Theme refers to the central idea or message conveyed in a literary work. In this case, the line 'And oftentimes, to win us to our harm, The instruments of darkness tell us truths?' from Shakespeare's play 'Macbeth' highlights the idea that evil forces can use the truth to manipulate and deceive.
Learn more about Theme in literature