Herodotus has been called by Cicero and others the 'father of history.' Living circa 490-425 BC, Herodotus set about writing his History, which covered not only the Persian Wars, but also the history of the two civilizations and what set them on the path to war.
Herodotus was born in Ionia, but traveled widely through the Greek world and Egypt. A masterful story teller, Herodotus relied heavily on the information that he gained in these travels to write his History. In this work, he ambles through diverse topics, from the Persian War to Egypt to lessons on morality. In this way, reading Herodotus seems less like a history and more like listening to the tales of an old man after a large dinner.
One of the central themes of his history is that the pride of man, caused by wealth and power, will lead to conflict with the gods and to eventual ruin. The oracles play a major role in his history, and Herodotus goes to great length to prove their infallibility. At other times, Herodotus tries to rationally examine the world with somewhat dubious results.
Because he was the first to attempt such a work, Herodotus was forced to rely heavily upon the oral traditions of areas he visited. Because of this later Greek and Roman scholars attacked Herodotus' credibility, believing him to be a liar. Modern scholars have found a much greater appreciation for Herodotus' accomplishments of preserving an oral history that would have otherwise been lost.
Herodotus. The Persian Wars.
Oxford Concise Companion to Classical Literature. ed. Howatson and Chilvers. Oxford. New York, 1993.