Insight

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Middle English (in the sense ‘inner sight, wisdom’): probably of Scandinavian and Low German origin and related to Swedish insikt, Danish indsigt, Dutch inzicht, and German Einsicht .

wiktionary

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From Middle English insight, insiht(“insight, mental vision, intelligence, understanding”), equivalent to in- +‎ sight. Perhaps continuing Old English insiht(“narrative, argument, account”), from Proto-Germanic *insahtiz(“account, narrative, argument”). Compare West Frisian ynsjoch(“insight”), Dutch inzicht(“insight, awareness, view, opinion”), German Low German Insicht(“insight”), German Einsicht(“insight, knowledge, perception, understanding”), Danish indsigt(“insight”), Swedish insikt(“insight”), Icelandic innsýn(“insight”).

etymonline

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insight (n.)

c. 1200, innsihht, "sight with the 'eyes' of the mind, mental vision, understanding from within," from in (prep.) + sight (n.). But the meaning often seems to be felt as "sight into" (something else), and so the sense shifted to "penetrating understanding into character or hidden nature" (1580s). Similar formation in Dutch inzigt, German einsicht, Danish indsigt.