Open Source, a radio program hosted by Christopher Lydon, recently pulled off something rather unusual. The broadcast (iTunes - mp3) made it abundantly clear why an Ancient Greek text, Thucydides' History of the Peloponnesian War, remains fascinating and highly relevant to modern day readers. Written 2400+ years ago, Thucydides has something important to offer history and military buffs alike, and also those who want to delve into the complicated human psyche. For historians, Thucydides' work gives us the first modern history -- the first historical narrative that looked to render the past in an analytical, empirical and objective way (a departure from the more literary, myth-based histories that came before it). For military thinkers, including students at West Point, the work holds such appeal because it recounts the epic, 27-year war (431–404 BC) between the two greatest Greek powers -- on the one side, Athens, a democratic but increasingly imperialist power, and, on the other side, Sparta, a harsh oligarchic power that held no particular imperial aspirations. Thucydides, an Athenian general, gives you the blow-by-blow account of a landmark historical war. But he also gives you more. What particularly engages readers, both past and present, are Thucydides' philosophical insights into human nature -- into how our passions and fears, particularly during times of war, can counter-productively undermine our civility and humanity. This applies to leaders and citizens of Athens, who overreached and eventually lost their war. Yet it also potentially applies to modern America because it is Thucydides' assumption that human nature remains fundamentally the same across time and place. And, in that sense, there is a cautionary tale for all of us in this seminal Greek work.