Explanation:
“He above the rest
In shape and gesture proudly eminent
Stood like a tower; his form had yet not lost
All her original brightness, not appeared
Less than archangel ruined, and the excess
Of glory obscured.”
(Lines 589-595)

Answer: These lines are taken from Milton’s ‘Paradise Lost’ Book-I, the great epic in the English language.

In these lines, the poet gives a wonderful description of Satan’s personality as the leader of the fallen angels when they had reassembled at his rejuvenating call and unfurled his banner to the play of Dorian music. Satan had a tower-like figüre and, among all the overthrown angels, he had the most striking body. His appearance had not as yet lost all the brightness which it possessed originally. Even in his ruined condition, he reminded one of having been the Archangel. The only change in him was that his erstwhile excessive glory had declined. Using abstract for concrete the poet emphasises that Satan’s form looked like something which had been excessively glorious, but was now somewhat diminished in splendour.

What Milton means to say is that before his revolt Satan had an ‘excess’ of glory like the sun, which is too dazzling to be looked at by the human eye. Now after his overthrow from Heaven, his radiance had been reduced as the suns can be, either by mist, when its disc is dulled, or by an eclipse, when it is wholly overshadowed.