5 infernall > internall 1590; eternall conj. Collier

1 At length they came into a larger space, 2 That stretched itself into an ample plain, 3 Through which a beaten broad highway did trace,

broad highway > (Cf. 104.2:8, 110.10:5) trace > proceed, pass

4 That straight did lead to Pluto's grisly reign:

grisly > fearsome, horrible reign > kingdom, realm

5 By that way's side there sat infernal Pain,

Pain > Punishment

6 And fast beside him sat tumultuous Strife:

fast > very closely

7 The one in hand an iron whip did strain,