In "Macbeth", why are the special powers of the king of England mentioned in Act 4, Scene 3?
Shakespeare is really appealing to the vanity of James I, king of England when the play was first produced. He calls kingly virtue:,
"justice, verity, temperance, stableness,
Bounty, perseverance, mercy, lowliness,(105)
Devotion, patience, courage, fortitude,..."
James I traced his lineage back to Banquo through Malcolm. Malcolm is testing Macduff by saying he has none of these qualities that a king must have. Malcolm realizes he probably does, or will try, to have these virtues, but first he wants to test Macduff to see if Macbeth sent him. Malcolm goes on and even attests to the English king's miraculous powers:
"A most miraculous work in this good King,
Which often, since my here-remain in England,(165)
I have seen him do. How he solicits heaven,
Himself best knows; but strangely-visited people,
All swol'n and ulcerous, pitiful to the eye,
The mere despair of surgery, he cures..."
He even suggests the English king is a prophet:
"He hath a heavenly gift of prophecy,
And sundry blessings hang about his throne(175)"
Through Malcolm, Shakespeare is implying that James I also has these "heavenly" qualities. Thus James would be far more inclined to support Shakespeare's plays, just as Queen Elizabeth had done. This shows Shakespeare's political intelligence.