The pilot: Saint Peter, figuratively introduced as the head of the Church on earth, to foretell "the ruin of our corrupted clergy, then in their heighth" under Laud's primacy.
the wolf: Popery.
Alpheus: a stream in Southern Greece, supposed to flow underseas to meet the Arethuse.
Swart star: the Dogstar, called swarthy because its heliacal rising in ancient times occurred soon after mid-summer.
moist vows: either tearful prayers, or prayers for one at sea.
Bellerus: a giant, apparently created here by Milton to personify Bellerium, the ancient title of the Land's End.
The great Vision:—The story was that the Archangel Michael had appeared on the rock by Marazion in Mount's Bay which bears his name. Milton calls on him to turn his eyes from the south homeward, and to pity Lycidas, if his body has drifted into the troubled waters of the Land's End. Finisterre being the land due south of Marazion, two places in that district (then by our trade with Corunna probably less unfamiliar to English ears), are named,—Namancos now Mujio in Galicia, Bayona north of the Minho, or, perhaps a fortified rock (one of the Cies Islands) not unlike St. Michael's Mount, at the entrance of Vigo Bay.
ore: rays of golden light. Doric lay: Sicilian, pastoral.
Poem 70.
The assault: was an attack on London expected in 1642, when the troops of Charles I. reached Brentford. "Written on his door" was in the original title of this sonnet. Milton was then living in Aldersgate Street.