Libra did not exist in the ancient world until very late. Before, Scorpio spread over two-twelfths of the zodiac and what we call Libra today was the Scorpion’s claws. As we can see from the night time sky, Scorpio is next to the great hunter Orion. Modern scholars assume that Scorpio had come from ancient Babylonian to the West. While that may be true, there is a question which we must always ask: "Why did the Greeks keep this monster and adopt it from the Middle East?" It is impossible to know.

As for Libra, they were the Chelae or Claws before they were transformed into the scales or balance. The change to a separate and different constellation appears to have occurred during Roman times when the claws were referred to as Jugum, the Voke or Beam, of the Balance. It was probably transformed, because of the autumnal equinox when Libra weighs and balances night and day. It appears that Libra does appear in the Julian calendar when it is instituted by Caesar who was then Pontifex Maximus.

By Kalev Pehme
winshop.com.au/annew/MythsZodiac.html

So I'm a mith :D.
Libra is the 7th sign of the zodiac and is remarkable for being the only one not represented by a living creature. Early zodiacs did not recognise the sign for it was only created in Roman times to separate and maintain the balance between the Virgo - Scorpio pair who are, according to Genesis, Eve crushing the Serpent's head and the Serpent, or Scorpion, striking at the Virgin's heel - a story with its basis in the turn of the year at the new moon following the Autumnal Equinox.
So I'm equilibirum :D.

Very interesting reading. Thanks for sharing. Karen

over the years  i have ran across different dates reg. the "cusp"    
i've heard  5 days from the cut date either way       oct 20..,    < so the 16 of oct would be considered cusp> as would oct 25>
and also i've heard 3 days  so that would make it  the 18 of oct.
   either way  i do find some scorpio traits surface in my life

i've never been able to find anyone that can state the real cusp dates..    or are there any real cusp dates.

I've read that the constellations of Virgo and Libra had very similar origins.  A goddess of justice, Astraea (I hope I spelled her name right).  She became the constellation Virgo, while her scales became the adjacent constellation of Libra.

Sol's abode in Libra is from the Autumn Equinox (September 23rd) until the 23rd of October...at least this year it is.  It can be early a day or late a day.  By 'day' I mean several hours that just happens to be on either side of 12 midnight.  This year, Sol entered Libra at 4:45am on September 23rd, and it enters Scorpio just before 2pm on October 23rd.