linguistic:paraphrasing, structural:reformatting
Critical interpretation

Scholars traditionally viewed Thucydides as recognizing and teaching the lesson that democracies need leadership but that leadership can be dangerous to democracy. Leo Strauss (in The City and Man) locates the problem in the nature of Athenian democracy, about which, he argued, Thucydides was ambivalent. Thucydides's "wisdom was made possible" by the Periclean democracy, which had the effect of liberating individual daring, enterprise and questioning spirit; this liberation, by permitting the growth of limitless political ambition, led to imperialism and eventually, to civic strife.

For Canadian historian Charles Norris Cochrane (1889–1945), Thucydides's fastidious devotion to observable phenomena, focus on cause and effect and strict exclusion of other factors anticipates twentieth-century scientific positivism. Cochrane, the son of a physician, speculated that Thucydides generally (and especially in describing the plague in Athens) was influenced by the methods and thinking of early medical writers such as Hippocrates of Kos.

After World War II, classical scholar Jacqueline de Romilly pointed out that the problem of Athenian imperialism was one of Thucydides's preoccupations and situated his history in the context of Greek thinking about international politics. Since the appearance of her study, other scholars further examined Thucydides's treatment of realpolitik.

Other scholars have brought to the fore the literary qualities of the History, which they see in the narrative tradition of Homer and Hesiod and as concerned with the concepts of justice and suffering found in Plato and Aristotle and questioned in Aeschylus and Sophocles. Richard Ned Lebow terms Thucydides "the last of the tragedians", stating that "Thucydides drew heavily on epic poetry and tragedy to construct his history, which not surprisingly is also constructed as a narrative". In this view, the blind and immoderate behaviour of the Athenians (and indeed of all the other actors)—although perhaps intrinsic to human nature—leads to their downfall. Thus his History could serve as a warning to leaders to be more prudent, by putting them on notice that someone would be scrutinizing their actions with a historian's objectivity rather than a chronicler's flattery.

The historian J. B. Bury writes that the work of Thucydides "marks the longest and most decisive step that has ever been taken by a single man towards making history what it is today".

Historian H. D. Kitto feels that Thucydides wrote about the Peloponnesian War, not because it was the most significant war in antiquity but because it caused the most suffering. Several passages of Thucydides's book are written "with an intensity of feeling hardly exceeded by Sappho herself".

In his book The Open Society and Its Enemies, Karl Popper writes that Thucydides was the "greatest historian, perhaps, who ever lived". Thucydides's work, Popper goes on to say, represents "an interpretation, a point of view; and in this we need not agree with him". In the war between Athenian democracy and the "arrested oligarchic tribalism of Sparta", we must never forget Thucydides's "involuntary bias", and that "his heart was not with Athens, his native city."

Although he apparently did not belong to the extreme wing of the Athenian oligarchic clubs who conspired throughout the war with the enemy, he was certainly a member of the oligarchic party, and a friend neither of the Athenian people, the demos, who had exiled him, nor of its imperialist policy.