Or > Whether Bacchus > (The god of wine, son of Jupiter and Semele) merry > {Delightful, characterized by festivity. Until about 1575, "merry" also meant, as again it does now, "tipsy"} invent > discover
3 Or Cybele's frantic rites have made them mad;
Cybele > (Or Rhea, wife of Saturn and mother of Jupiter, a goddess worshipped by the Corybants with frenetic music and dancing. Cybele's priests practised self-castration, which may account for the reference to her here: cf. the libidinous satyrs at 310.44 ff.)
4 They, drawing nigh, to their god present 5 That flower of faith and beauty excellent.
excellent > supreme
6 The god himself, viewing that mirror rare,
mirror > reflection [of perfection]; hence: paragon of beauty
7 Stood long amazed, and burnt in his intent;
intent > attention; mental activity; hence: gaze
8 His own fair Dryope now he thinks not fair,