"Human nature being what it is"

Thucydides was one of the books assigned for my international relations theory class in graduate school. This essay, "A Possession for All Time," is a good introduction and explains why this ancient history is still important:

On August 11, 1777, John Adams, then a delegate to the Second Continental Congress in session in Philadelphia, wrote a letter to his ten-year-old son, John Quincy. In light of the ongoing War of Independence and with a mind to other wars and “Councils and Negotiations” that the future might hold for the boy, Adams urged him “to turn your Thoughts early to such Studies, as will afford you the most solid Instruction and Improvement for the Part which may be allotted you to act on the Stage of Life.” He gave one recommendation in particular: “There is no History, perhaps, better adapted to this usefull Purpose than that of Thucidides.” For Adams, Thucydides’ History of the Peloponnesian War contained within it insight of every possible “usefull” sort: “You will find it full of Instruction to the Orator, the Statesman, the General, as well as to the Historian and the Philosopher.”

For centuries, Thucydides has been made to wear each of those very hats. Politicians and military personnel, historians, political scientists, and classicists have all laid claim, often in radically different ways, to his work and wisdom. Today, the History enjoys a status—in university curricula, among political theorists, and in military and policy communities—as a foundational source for theorizations of democracy, international relations, war, and human and state behavior. Thucydides himself might not be disappointed to know this, for toward the beginning of his History he announces that he has composed his work with future ages in mind:

Perhaps the lack of fantastical material here will seem charmless to my audiences. Nevertheless, I will be content if anyone who desires to gain a clear understanding of past events, and of future events that will one day resemble the past more or less closely—human nature being what it is—finds my work useful. This work was composed to be a possession for all time and not as a showpiece to be heard for a fleeting moment. .... (more, from a very good essay)

A Possession for All Time | Lapham’s Quarterly