What is the importance of a nation? Use political theory or historical examples.

I think that the importance of a nation as a functioning
and cohesive unit can be seen in the case of post- Revolution America.  After gaining
independence from England, America adopted the Articles of Confederation as its
governing constitution.  This document pretty much defined the nation as a "loose
confederation of states. " States were able to act in opposition to one another and
there was nothing in terms of acting in concert or convergence towards a national
identity present.  Part of this was a result of the fears of the framers in repeating
the same conditions of tyranny as existed with King George and England.  Yet, while the
states had freedom, they lacked a national identity or the need to seek national
consensus.  This could be seen in the federal government's inability to raise taxes and
generate revenue, sorely needed to pay off a debt from the American Revolution.  At the
same time, the lack of a national focus made the new confederation susceptible to
threats from other nations.  Finally, when Shays' Rebellion grew in force and magnitude,
there was not a coordinated and concerned national response to such an
uprising.

I think that this is where one sees the
importance of a nation.  The need for individual states to act with a singular purpose,
while being able to express their own individuality contributes to a stronger vision. 
This is where tranquility can emerge and prosperous foundation can be present.  When
there is a lack of this national focus, greater risks to these elements are
present.