Quote 1
FERDINAND
The ditty does remember my drowned father.
This is no mortal business, nor no sound
That the earth owes. I hear it now above me. (1.2.483-485)
Magic is more than mortal, though it tends to impact mortals. Ferdinand draws the connection that magic might also have a bit of the divine in it (otherwise it would be against God, and kind of blasphemous).
Quote 2
FERDINAND
This is a most majestic vision, and
Harmoniously charmingly. May I be bold
To think these spirits?
PROSPERO
Spirits, which by mine art
I have from their confines called to enact
My present fancies. (4.1.131-136)
Prospero is not above using his magic to his own fancy. We are asked to think about the limitation of his power here—he can make spirits look like gods, but he has no access to the real gods. Is the implication that even Prospero's magic hits a glass ceiling when it comes to the divine?
Quote 3
FERDINAND
Might I but through my prison once a day
Behold this maid. All corners else o' th' earth
Let liberty make use of. Space enough
Have I in such a prison. (1.2.597-600)
Although Prospero has made a big show of bullying Ferdinand, the prince insists that as long as he can see Miranda, he's free enough. That's kind of sweet but also a little scary, don't you think?