His sad exclusion from the doors of bliss.
Astronomy, it is suggested by "the affable Archangel," has perhaps been made a difficult subject in order to produce the droll fallacies of astronomers:
He his fabric of the Heavens
Hath left to their disputes--perhaps to move
His laughter at their quaint opinions wide.
And this conjecture is borne out by what happened when the builders of the tower of Babel were frustrated, for then--
Great laughter was in Heaven,
And looking down to see the hubbub strange
And hear the din.
Milton, in short, has hardened the heart of the God that hardened Pharaoh's heart, and has narrowed his love and his power.