After again seeing the secret of life unfold infinite sufferings, an
alien civilization chose to currate evolution to prevent new species
experiencing true atrocities.

A pervasive seeker program was implemented.  Worlds were observed,
catalogued, and monitored by a vast network of drones.  If artificial
quadrilaterals were detected, the seeker added the world to queue to
be handled by the controllers.  Occassionally, false positives such as
crystal would be picked up, but the seeker program is continuously
updated with refined identification schematics such that these
anomalies are rare.  The quadrilaterals detected define the state of
progress for the species.  In some cases, cave paintings or megaliths
are identified.  Most often, the seeker will not make contact until
the creatures have started making buildings with rectangular facades.
Most rarely, a civilization has embarked into space-faring before they
are observed.

Once a crafted quadrilateral is identified, the controller chooses the
appropriate course of action.  Initially, almost all cases are
recognized as valid but requiring more monitoring.  The seeker then
sits and gathers information on the rise of the civilization.
Controllers with such expertise can determine from species movements
what wars and wedding parties take place.  If the civilization
survives to discover broadcast radio, a more intimate glimpse of their
substance may be gained almost overnight.  The violence and
technological progress of the species arefiled.  
Monitoring programs may last for centuries or millinea.  Occassionally
the controllers are fortunate: an accident of nature will kill off the
fledgling species before the decision is put upon them.

Once a civilzation reaches a natant phase, their file is assessed.
Their wars are recounted, their crimes named.  A planet-killer is
dispatched and all affected life is destroyed.  For somet time, debate
was attended on whether it was fair to remove all life for the sake of
the offending species.  In the end it was concluded that the planet
was forever contaminated and to leave around remnants was only to
introduce a dangerous and unnecessary variable.

The civilization and all other life is destroyed humanely.  Great
cares are taken to that end, and though they could neither know of or
appreciate their demise, the controllers were giving them the greatest
act of mercy.  To join universal ephemerality without the horrors of
Nazi medical experiments, brain tanks, pain amplifiers, and knowledge
of the philosphic trap that awaited them all in the end; for this,
their gratitude could be imagined.

The alien civilization developed a metric of judgemnet for if a
civilization should be eliminated.  If they could be seen on a path of
enlightenment without the paragraphs of pain, they were to be spared.
So far, none has been spared.