Macbeth: But in these cases We still have judgment here; that we but teach
Bloody instructions, which, being taught, return
To plague the inventor: (1.7.8-11)
Commentary: Macbeth's speech reflects the common biblical theme known best by the passage from Galatians 6.7: "Be not deceived: God is not mocked: for what so ever a man soeth, that shall he also reap". The theme is continued in Job 4.8: "They that plow iniquity and sow wickedness, reap the same"; and in Wisdom of Solomon 11.13: "Wherewith a man sinneth, by the same also shall he be punished."
Macbeth: I have no spur
To prick the sides of my intent, but only
Vaulting ambition, which o'erleaps itself (1.7.25-7)
Commentary: The "vaulting ambition" to which Macbeth refers is the pride so condemned in the Bible. In Matthew 23.12 we read: "For whosoever will exault himself, shall be brought low"; and in Proverbs 29.23 we read: "The pride of a man shall bring him low". Proverbs 16.18 tells us that: "Pride goeth before destruction, and a high mind before the fall."