[249-252.] Even darkness smiled, as if acknowledging itself agreeably caressed by the strains of the lady’s song.
[251. At every fall.] Fall, as a musical term, is “a sinking down or lowering of the note or voice; cadence” (New Eng. Dict.).
[253. the Sirens] dwelt on an island near Sicily, and by their sweet song allured mariners to destruction. See Odyssey XII.
[254. the Naiades] were nymphs attendant on Circe and the Sirens.
[257. And lap it in Elysium.] Compare [L’Allegro 136].
[257-259. Scylla and Charybdis] were dangerous rocks and whirlpools on opposite sides of the strait of Messina. They were personified as cruel sea-monsters.
[260. Yet they:] Circe and the Sirens.
[267. Unless the goddess.] Supply thou art.
[273. extreme shift:] a pressing necessity of devising some expedient.
[289. Were they of manly prime or youthful bloom?] Were they in the prime of adult manhood, or in the bloom of youth?