there may
   or may not
exist
certain colours
that the human eye
is unable
to see
an insipid
   blueish-yellow
an unpalatable
   greenish-red
each said
to be impossible
for our eyes
to process;
if seen
it could appear
in all manner
of forms
but would remain
indescribable

they say that
butterflies can see
the ultraviolet spectrum
and that
the honey bee
sees in infrared;
and so
it would not
be too absurd
for a person
to dismiss
the "impossible"
to believe
in the possibility
of the as-yet
unseen

although
scientifically
the only way
to perceive
these "forbidden" hues
is through trickery
and constraint
by forcing the brain
into seeing both
antagonistic colours
simultaneously
and
without reprieve
until the border
between
the opposing shades
finally dissolves

there may be
a truth
but it is hidden
somewhere between
the plausible
   yet impalpable
and the proven
   yet proselytised