The Golden Rule

Confucianism
     What you don't want done to yourself,
     don't do to others
     - SIXTH CENTURY B.C.

Buddhism
     Hurt not others with what pains thyself.
     - FIFTH CENTURY B.C.

Jainism
     In happiness and suffering, in joy and grief,
     we should regard all creatures as we regard our
     own self, and should therefore refrain from
     inflicting upon others such injury as would
     appear undesirable to us if inflicted upon
     ourselves.
     - FIFTH CENTURY B.C.

Zoroastrianism
     Do not do unto others all that is
     not well for oneself.  
     - FIFTH CENTURY B.C.

Classical Paganism
     May I do to others as I would
     they should do unto me.
     Plato - FOURTH CENTURY B.C.

Hinduism
     Do naught to others which if done thee
     would cause thee pain.
     Mahabharata - THIRD CENTURY B.C.

Judaism
      What is hateful to yourself,
      don't do to your fellow man.
      Rabbi Hillel - FIRST CENTURY B.C. 

Christianity
      Whatsoever ye would that men should do to you, 
      do ye even so to them.
      Jesus of Nazareth - FIRST CENTURY A.D. 

Sikhism
      Treat others as thou would be treated thyself.
      - SIXTEENTH CENTURY A.D.

All of this strongly suggest that among human beings there is wide agreement about at least one general ethical principle.

And it is a sensible and humane rule, however it is precisely formulated. It also has the merit to appeal to the common human nature all humans share, but it is clearly not by itself a sufficient foundation for human society, since history shows that the Golden Rule has often been broken, and is easy to break as soon as human beings consider someone else, rightly or not, as an enemy or as a stranger or as a member of faith they don't share or as someone whom one can without punishment maltreat or deceive in one's own interests.

In brief: The Golden Rule in practice holds mostly only between friends and supposed equals, and otherwise has been often and easily broken.