The cross was a symbol that someone else had the power, even power to put Jesus to death.  It looked like the empire had triumphed with the last word.  “King of the Jews”, in mockery, was put over the cross.  But the one with the real power was not Caesar, Herod, nor Pilate.  Messiah demonstrated His power, not by military might, not by returning evil for evil, nor death for death, and without vengeance, retaliation and retribution He showed the kind of power that the weak can never show.  He showed the radical power of unconditional love, unearned mercy, and complete forgiveness.  There is no power in the universe which can match that.