Commentary Par IX 127-129

Satan is traditionally thought of as prideful (in that he cannot accept being less important than God); but he is also thought of as envious, particularly in his dealings with Adam and Eve, whose happiness he cannot abide.  Dante uses the rhetorical figure periphrasis here to rousing effect, for who does not know the 'answer' to this riddle?  We seem to be invited to shout the name of Lucifer.  But note also the crushing result when we consider the adverb pria (first): Satan may have been the first to deny his Creator, but he was hardly the last, dear reader....

The sins of Eve and Adam brought all of us 'distress' in that we weep for our lost immortality.

For Satan's fall as a 'foundation myth' of humankind, see C.Inf.XXXIV.121-126.  This text would seem to offer another version of that myth, with Satan's envy as the founding sin of Florence.