Final answer:
Banquo speculates that if Macbeth's prophecy of becoming king comes true, the prophecy about his own descendants becoming kings might also be correct. He remains cautious and loyal, in contrast to Macbeth, maintaining his integrity despite the tempting prophecies.
Step-by-step explanation:
Within William Shakespeare's play Macbeth, Banquo contemplates the possibility of the witches' prophecies coming true not just for Macbeth, but for himself as well. After Macbeth is told he will be king and Thane of Cawdor, Banquo reasons that if these predictions hold true for Macbeth, then it might also be likely that his own progeny will someday become kings as the witches foretold. This is based on the witches' prediction that while Macbeth shall be king, it is Banquo's descendants who are destined to inherit the throne in the long term.
Banquo's cautious approach to the prophecies contrasts with Macbeth's ambitious and eventually murderous actions. Banquo wishes to keep his 'bosom franchised and allegiance clear,' implying that he does not want to compromise his integrity or loyalty to gain power or ensure the prophecies' fulfillment. His consideration of the future portrays a character that, unlike Macbeth, is not willing to give in to temptation and commit evil deeds, even if it may result in power or benefit for his lineage.