In a message dated Mon, 21 May 2001 3:35:25 PM Eastern Daylight Time, Rickard A Parker <[log in to unmask]> writes:
<< Since the puns in the ivory and horn gates were Greek I thought that
the use of these symbols must have pre-dated Virgil so I poked around
the internet a bit more and found this:
. . .
Written 800 B.C.E
Translated by Samuel Butler
Even that looks like it might not have been the first source but I
don't care any more. I give up.
Rick Parker >>
It must have been kicking around if Homer used it, but if you find an earlier written source of greek mythology than Homer, you'll have quite a scoop!