Suppressed scene from Schiller's Die Räuber (1781):
FRANZ: I do not know, Maurice, if you have read Milton. He who could not endure that another should be above him, and who dared to challenge the Almighty to a duel, was he not an extraordinary genius? He had encountered the Invincible One, and although in defeat he exhausted all his forces, he was not humiliated; eternally, even to the present day, he makes new efforts.
From James Beattie, Dissertations Moral and Critical (1783):
Satan, as Milton has represented him in Paradise Lost, though there are no qualities that can be called good in a moral view…yet there is a grandeur of a ruined archangel; there is force able to contend with the most boisterous elements; and there is boldness which no power but what is Almighty can intimidate. These qualities are astonishing; and…we are often compelled to admire that very greatness by which we are confounded and terrified.
From William Blake, The Marriage of Heaven and Hell (1790):
The reason Milton wrote in fetters when he wrote of Angels and God, and at liberty when of Devils and Hell, is because he was a true Poet and of the Devil's party without knowing it.
From Maximilian Rudwin, The Devil in Legend and Literature (1931):
Satanism is not a part of Romanticism. It is Romanticism. It may well be said without any levity that Satan was the patron saint of the Romantic School.
(Illustration is John Martin, The Fallen Angels Entering Pandemonium, 1841.)