603. ~grisly legions~. 'Grisly,' radically the same as _grue-some_ =
horrible, causing terror. In _Par. Lost_, iv. 821, Satan is called "the
grisly king." 'Legions' is here a trisyllable.
604. ~sooty flag of Acheron~. Acheron, at first the name of a river of the
lower world, came to be used as a name for the whole of the lower world
generally. Todd quotes from P. Fletcher's _Locusts_ (1627): "All hell
run out and sooty flags display."
605. ~Harpies and Hydras~. The Harpies (lit. 'spoilers') were unclean
monsters, being birds with the heads of maidens, with long claws and
gaunt faces. _Hydras_, here used as a general name for monstrous
water-serpents (Gk. _hyd{=o}r_, water); the name was first given to the
nine-headed monster slain by Hercules. See _Son._ xv. 7, "new rebellions
raise Their _Hydra_ heads"; the epithet 'hydra-headed' being applied to
a rebellion, an epidemic, or other evil that seems to gain strength from
every endeavour to repress it.
607. ~return his purchase back~, _i.e._ 'give up his spoil,' or (as in the
MS.) 'release his new-got prey.' To purchase (Fr. _pour-chasser_)
originally meant to pursue eagerly, hence to acquire by fair means or
foul: it thus came to mean 'to steal' (as frequently in Spenser, Jonson,
and Shakespeare), and 'to buy' (its current sense). See Trench, _Study
of Words_; _Hen. V._ iii. 2. 45, "They will steal anything, and call it
_purchase_"; i. _Hen. IV._ ii. l. 101, "thou shalt have share in our
_purchase_."