The reason Milton wrote in fetters when he wrote of Angels & God, and at liberty when of Devils & Hell, is because he was a true Poet, and of the Devils party without knowing it.
ATTRIBUTION:
William Blake (17571827), British poet, painter, engraver. The Marriage of Heaven and Hell, plate 6, The Voice of the Devil, (c. 1793), repr. In Complete Writings, ed. Geoffrey Keynes (1957).