As mankind began to develop more complex ways of life, and as cities began to increase in size and complexity, a new type of society emerged. These societies are known today as civilizations. A civilization is a nation or people that share a common culture, common laws, a common economy, and typically a common faith or religion.
To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge.
The Mesopotamians were the first people to keep records of lunar eclipses, beginning in 2200 B.C.