The History of the Peloponnesian War was not written of only one jet (the current division of the work in eight books is convenient but artificial). It stops into 411, before the effective end of the hostilities, and opens by a short foreword where the author exposes his method, followed by a “Archeology” where he recalls the development of the Greek history since the origins (I delivers). The account of the fratricidal fights between Athenians and Lacédémoniens proceeds in three times: until the peace of Nicias (books I with V), the forwarding of Sicily (books VI and VII), various operations until 411 (book VIII).

Historical method of Thucydide

The history, according to Thucydide, could be only that of the time present, which one can carry out an autopsy on (with the etymological direction “to see its own eyes”), and not that one hears in the accounts of memory. On this point, it fraudulently registered against his elder Hérodote (towards 484 - towards 420 av. J. - C.), which he treats of logographe, i.e. of “teller of stories”.  

The direction of the rational analysis
Eliminating from its account the marvellous one and the providentialists explanations, Thucydide rather tries to dismount the mechanism of the war, to understand of them release (“the two people had arrived at the top from their power”, L.I, 1) and the multiple adventures. Its analysis of the Athenian imperialism, even if it excludes the properly economic determinations, makes still today the admiration of the historians. It is not completely impartial (in spite of its exile, Thucydide remains Athenian and is acknowledged near to the moderate aristocrats), but it endeavors to be released from the passion explanations.  

The composition
A rigorous chronology, the use not only of its own memories but also of testimonies and varied and precise documents, their confrontation are the bases of its historical method. Its work appears, with many regards, like a genuine “rationalist proclamation” (J. of Romilly). It is also a work of art of which the composition overall, simple and structured, organizes itself around dense and vigorous accounts (that of the plague of Athens, which in 429 av. J. - C. was going to carry Périclès, remained very famous) and of fictitious speeches where bursts the power oratory of the pupil of the sophists. This last process of exposure enables him to introduce in to an alive way at the same time the men and their political programs. The historian intervenes directly only by short judgments where it releases the direction of the events which it has just reported.  

Style
The style of Thucydide was subject to the influence of the rhetors: it uses the antithesis constantly, does not hesitate to make use of neologisms, and its concern of the concision sometimes made it show of darkness (Cicéron already found it not easily understandable). These darknesses, these ruptures of construction, these abrupt sentences are the clearest demonstrations of the difficult work of the historian, who unceasingly seeks to specify, to however explain rationally, and refuses with simply diverting.  

Thucydide gives to the history an autonomous statute, manages to move away it from the myth, it in fact, like itself says it, “a treasure for always”, i.e. reference an index, a true science.