Have you looked it up in Bartlett's _Familiar Quotations_ and
other similar references?
Henry Grunder
Conservation/Preservation Coordinator
The Library of Virginia
                    "Hustling libraries shamelessly"
According to [log in to unmask]:
>
> Anyone know what philosopher said this and what it means?:
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> "The owl of Minerva spreads its wings and takes flight only at dusk."
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> TIA,
>
> - Adrienne
>