Historians have often discussed the causes of the outbreak of the "Great War between Athens and Sparta". Indeed, it seems strange that two city-states, who had fought side by side against Persian invaders not fifty years before should turn on each other in a bloody war. The principal source by which this period can be examined is Thucydides, son of Olorus, an Athenian naval officer. In his introduction, he examines the causation for the war and defines two distinct areas of examination. Firstly, he highlights the "alhqhstathn projasin" truest cause as being the imperialism of Athens, but also acknowledges the...
fear thereof in Sparta was the "alhqhstathn projasin" of the war. It is tempting to dismiss Thucydides as a biased Athenian; this, however, is not fair either. As Henderson says, he is "chary of advertising his own judgments" and is very advanced for his time seeking as much of the truth as possible. The progression of Athenian imperialism, from independence to a growing empire to a "domination and monopoly" is a history scattered with ever-growing friction between the two powers of Greece and every event or conceptual tension stems from and relates to the growth of Athenian imperialism.