"when the battle's lost and won" and when "fair is foul and foul is fair"
On a heath in Scotland, three witches, the Weird Sisters, wait to meet Macbeth amidst thunder and lightning.
he's "too full o' th' milk of human kindness”
Duncan, king of Scotland, meets a captain returning from battle. Duncan decides to execute the disloyal thane and give the title of Cawdor to Macbeth.
Duncan then states that he plans to visit Macbeth at his home in Inverness. Macbeth leaves to prepare his home for the royal visit, pondering the stumbling block of Malcolm that now hinders his ascension to the throne.
At Inverness, Lady Macbeth reads a letter from Macbeth that describes his meeting with the witches.to murder Duncan and assure the completion of the witches' prophesy. He has ambition enough, she claims, but lacks the gumption to act on it.