How did different governments further divide ancient Greeks? Could it complicate communication in times of war when they needed to band together? Explain.​

The topic of the essay:  a. the purpose of government.

I won't write your essay for you, but as a Teacher can provide some advice as you prepare to write.  Lincoln's assertion is that the proper purpose of government is do for the people of a nation or community what individuals could not do very well if they each tried to do it themselves.  You might think of examples like infrastructure -- road building, ports, public utilities -- as matters that need community to come together rather than "every man for himself."  Similarly, matters of public safety like police protection in cities or national protection through a military are better done by a government working as a cooperative entity of the citizenry, rather than expecting each individual to provide all of his own protection and security.  There could be many other examples (including a contested one, such as health care) that could be used to give support in agreement with Lincoln's argument.