impossible to write accurately about the past; his methods and his standards of proof are applicable only
to the present. He is a social scientist, a student of the contemporary world, not a historian. It was not
until the nineteenth century that the discovery of archives and the invention of the techniques of source
criticism allowed historians of the past to believe that they could meet the standards demanded by
Thucydides. And it was not until this century that these standards could even begin to be applied to the
study of Greek history, with the publication by F. Jacoby of the fragments of the lost Greek historians.
One area illustrates well Thucydides' advance on Herodotus: his account of the causes of the war.
Contemporaries found Herodotus' frivolous mythology of rape and counter-rape, from Io to Helen of
Troy, hilarious, and failed to note the problem that a clash of cultures ultimately leads to a war whose
causes are incapable of being isolated, inherent in the nature of the societies in question. In the case of
Greek city-states, however, there were established rules of international relations: an act of aggression or
the refusal of a just request were causes of war which had an overt political nature. It is to Thucydides'
credit that he does not remain on this level of claim and counter-claim. Instead he argues in detail for
two episodes as the generally accepted grievances which led to war, and for a 'truest cause seldom
mentioned explicitly'. The two episodes were military adventures involving a clash of interests and of
military forces between Athens and Sparta's leading ally, Corinth. The nature of 'the truest cause' is
harder to define, and it is indeed described as a personal opinion-'the Athenians becoming great and
provoking fear in the Spartans compelled them to fight' (1.23). Is this a statement about social
psychology, or an assertion of inevitability? How unmentioned was it, and where does it leave
responsibility for the war? These questions have been endlessly debated; here we need only note the
sophistication of a view which goes behind the diplomacy, and asserts two types of forces at work, two
levels indeed of causation. It is this abandonment of the obvious, and of the idea of a single cause or
type of cause, which is the decisive step in our understanding of the idea of causation in human affairs.
Where did Thucydides learn his method? The theory of politics and society was still in its infancy, and
there is nothing of comparable depth in any contemporary sophist. The medical writers operated with
ideas of underlying disposition to illness, and active cause for it, not unlike those of Thucydides, and
they had developed a science combining theory with practical insight which was analogous to his. But
we have only to read Thucydides' account of the Great Plague at Athens in Book 2 to see his superiority
even in describing a medical phenomenon: no contemporary medical writer has his clear description of
the two central medical concepts in disease of contagion and immunity. In fact we may say with
confidence that Thucydides' conception of social and historical method is his own creation. The problem
of Thucydides is essentially his isolation.
This conclusion is reinforced by consideration of Thucydides' literary style. It derives ultimately from
the antithetic periods of contemporary sophistic orators; but these have been twisted to present a
succession of broken opposites and ill-matched pairs, where no one word is the obvious word and each
phrase is unexpected. Its vice is that the simple becomes tortuous, the complex incomprehensible; its
virtue is not in its precision (for the precision is a false one), but in the way that it forces the reader-even
the contemporary Greek reader-to consider the exact significance and placing of every word. No other
Greek ever wrote or thought like Thucydides.