But in these cases / We still have judgement here; that we but teach / Bloody instructions, which being taught, return / To plague th’ inventor.
Act I, Scene 7 · Macbeth
Context
Still deliberating alone, Macbeth considers the broader consequences of regicide, imagining how violence sets a precedent that will come back to harm its originator.
Analysis
Macbeth frames murder as a lesson that 'returns / To plague th' inventor,' using the language of teaching and learning to describe political violence. This transforms killing a king into something that educates others—an instruction manual for future murderers—which traps Macbeth in a logical bind: if he teaches this lesson, someone will inevitably use it against him.
Essay Tip
Support a thesis that Macbeth understands power in cyclical, self-destructive terms before he even acts—he sees clearly that seizing the throne through murder guarantees he will lose it the same way, yet chooses it anyway.