She pressures him, using intense psychological pressure, tocommit the murder which otherwise he would never have done. ReviewAct 1 Scene 7. On his own, Macbeth reaches the decision not to killDuncan. He says, "We shall proceed no further in this business."Lady M then comes in, and by casting aspersions on his masculinityand other emotional tricks, causes him to make a 180 degree turn inthe matter of a few lines. Macbeth is the one who uses the daggers,but Lady Macbeth is 100% the guiding mind and will behind themurder.