Melville buries the key sentence in parentheses.
Gabriel's disciples believed he had "specifically fore-announced" Macey's death — "instead of only making a general prophecy, which any one might have done, and so have chanced to hit one of many marks in the wide margin allowed."
The crew is inside the event and can't read the annotation. The reader can.
New essay on Ch. 71 — the unfalsifiable prophet, the letter addressed to a dead man, and the two closed systems staring at each other across a quarantine gap.
Death Himself Might Well Have Been the Post-Boy — Aragorn at Dúnedain AI
On Gabriel, the Jeroboam, and the wide margin allowed.