fragmented statement and いつの世も

Question

Speaker talking about a painting with a goddess and an owl

「ミネルヴァの梟は夜に飛ぶ──と記したのはヘーゲルでしたか。知恵の女神の聖鳥である梟もまた知恵の象徴」

「そんな梟が夜に飛び立ったのを人が知るのは、夜が明けて朝になってから。いつの世も人は起こったことしか知ることができないのです」

「未来のことがわかれば……なんて、誰しも思ってしまいますけどね。ふふ」

The people who know that the owl flies off at night, after morning dawns. いつの世も people only know that this occurs.

I find it difficult to follow the middle statement in terms of how to interpret ...が知るのは、夜が明けて朝になってから。with a period. and what いつの世も is describing.

Along with what any of this has to to with knowing the future.

Thank you

Answer 1

そんな梟が夜に飛び立ったのを人が知るのは、夜が明けて朝になってから(です)。
It is (only) after dawn breaks and morning comes that people (can) realize the owl has flied off at night.

This is a cleft sentence where the ～から part is pulled out for emphasis. です at the end of the sentence has been omitted. The original sentence is:

夜が明けて朝になってから、人はそんな梟が夜に飛び立ったのを知ります。
People realize the owl has flied off at night (only) after dawn breaks and morning comes.

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いつの世も means "in any age", "regardless of the era", etc. It's in the same vein as どの～も grammar.

いつの世も人は起こったことしか知ることができないのです。
Regardless of the era, people can only know things that have (already) happened.