what song the sirens sang?

...asked Sir Thomas Browne; interesting question! Poe agreed and quoted it at the beginning of the Rue Morgue story. But what sort of answer did Sir Thomas expect? He asks another about the dead in Hades: Agamemnon can predict Ulysses' future but has nothing to say about his own son. It is a mistake to see this as contradictory; Browne's interest is not empirical (eg did Atlantis exist and where?).
Kafka brings up the issue of the sirens and his conclusion gives a clue as to the sort of answer that is required; K's approach is more akin to a parable; while Browne is not writing a parable he is asking questions (occasionally) that fit into a parable. K's answer is that the sirens are silent and Benjamin's explanation of why this is so would have interested Sir Thomas Browne.