Ambition is good, but it is what one ends up doing with that ambition that eventually seals their fate. It is well known to be saturated with themes and motifs that are repeated throughout the play.
One assumes that Macbeth is bloody just like the soldier.
As their guilt grows, so does the importance of the blood. Motifs of this narration are represented through the use of various events and some specific symbols.
His conscience is self-accusatory. In many Shakespearean plays — including this one — rebelling nature shows a departure from accepted political and moral order.
Once he kills his friend Banquo, who returns as a ghost, Macbeth tells that "blood will have blood" 3. The blood metaphor reveals a fundamental attitude change in Macbeth.