Two people might witness the event but not necessarily have the same point of view. Some people might be experts in a certain area, like warfare or being a ship's captain, and therefore might be more qualified to say what actually happened than someone without that expertise. Both people could be telling the truth as they saw and heard it, but the actual events might be different. In addition, some people might be biased, and their personal opinions of an event could influence their account.
The construction of democracy has its bases going back to ancient Greece. The guarantee of equal rights to all citizens, however, has only been legally possible due process of propagation of the notions of human rights, guaranteeing equal protection for all individuals.
