there was a time, thousands of years ago, when the Jedi listened only to the will of the living force, existed as symbiotes with it, and acted as extensions of the force itself: as manifestations of this "living force" in the 'real world'.
enter: the old republic -->
the Jedi became alligned with the galactic senate and started acting on the Will of the People instead of the Will of the Force.
they were bound by law to enact the will of the senate.
they became the living extensions of a political system,
which eventually, fell under direct control of the Sith.
by the time of ROTS ---> the Jedi were
using the force to act out the will of the Sith:
to fight a war for security, driven only by the people's FEAR.
they had ignored the "Will of the Force" for generations upon end,
and they acted ONLY on the "Will of the People" (via the galactic senate)
they represented the Common Good, which changes from day to day;
the abandoned the Universal Good, as defined by the will of the force.
in the end they had become no better than a common sith:
they DID NOT use the force, to enact the will of the force (aka: BALANCE)
they used the force to enact the will of the people (which was corupt);
they used the force to enact the Will of a Sith Lord (whether they knew it or not)
--->
thats why they had to be destroyed.
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in the end, Quigon was NOT leaning towards the dark side, as suggested in this thread ;
he wasn't 'walking the line between light and dark'
Qui gon was actually the penultimate Jedi: he was the
definitive Jedi:
he was trained to heed the Will of the Living Force,
even if it meant defying the Will of the People (even if it meant defying the jedi council)
meanwhile the Jedi Coulcil were bound by law to enact the Will of the People;
they didn't heed the will of the force,
and
hadn't been heeding it, for about a thousand years by this time.
they fell into a situation, where they were bound by law, to
USE THE FORCE, to act out the designs of a Sith Lord.
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Mace windu, with his odd-colored purple sword, represents the Jedi Order's ties to Law and Order.
Mace is the Link, between the Jedi of old, and the laws of the Galactic Senate (which is corrupt).
Mace embodies a political contract between the Jedi and the Senate,
to use the force, to enact the Will of the People.
problem : Sidious embodies the Will of the People. "
I AM the senate!" (heh)