Final answer:
Macbeth's trust in the second and third prophecies is reflected in his actions and the confidence he and Lady Macbeth have in his rise to power, turning prophecies into self-fulfilling deeds.
Step-by-step explanation:
In Macbeth, the titular character places his trust in the second and third prophecies given to him by the Apparitions. These prophecies emerge after Macbeth has already been made Thane of Cawdor, a title predicted in the first prophecy which impresses him due to its accuracy. When the witches hail Macbeth as the future king, despite the seeming improbability at the time, his ambition is kindled. Upon being formally given the title of Thane of Cawdor by King Duncan, Macbeth considers the witches' prophecies with a new seriousness, evident in his aside where he ponders the 'two truths' told as 'happy prologues' to the 'swelling act of the imperial theme.'
His friend Banquo notes that the witches have shown some truth, which further bolsters Macbeth's confidence in their words. Driven by the seemingly infallible assurances of his eventual kingship—implied by the prophecy—Macbeth, with the manipulative encouragement of Lady Macbeth, decides to murder King Duncan. The trust in these ominous predictions paves the way for Macbeth's subsequent actions based on the witches' assurances, showcasing his growing reliance on their prophetic words as a guide for his own ambitious but perilous path to power.