Mendelsohn explains the famous Herodotus’ digressions as means for the history of the Persian Wars to be incorporated into a vision of a cosmic history or of the nature of cosmos (world/existence). Mendelsohn seems quite right to me; I’d like to add only that Herodotus didn’t give birth to History out of nothing. A cosmic vision exists already from the time of Homer and then in Hesiod (in the latter even a History of the Cosmos).

Herodotus’ achievement was not something new, but on the contrary, it was the fact that he managed to found historical analysis inside the philosophical / poetical demand of a greater scale of thinking. This achievement was then followed by Thucydides. Thucydides may sound more ‘clinical’, but he speaks about the nature of man, he does not describe with the greatest possible accuracy historical events, he refers essentially to the future, and in his analysis he searches for natural laws governing this history, making of his material exemplary/characteristic/ideal appearances of the laws of a history which is formed according to the nature of human beings.

There is a relative decrease in the importance of the metaphysical element as we go from Homer, to Hesiod, to Herodotus, to Thucydides, which corresponds to the increase of the importance of the historical element. Homer already new how tragic history is, and the later generations were going to explore this tragical sense, never doing history just for an exact description of facts. Their aim was to explore the tragical nature of history, an aim which included a metaphysical stand – even when that was not apparent.

Daniel Mendelsohn: What was Herodotus trying to tell us? – Excerpts, selected by Ellopos (full text here).

History—the rational and methodical study of the human past—was invented by a single man just under twenty-five hundred years ago, Herodotus, known since Roman times as “the Father of History.” Herodotus’ Histories—a chatty, dizzily digressive nine-volume account of the Persian Wars of 490 to 479 B.C., in which a wobbly coalition of squabbling Greek city-states twice repulsed the greatest expeditionary force the world had ever seen—represented the first extended prose narrative about a major historical event. (Or, indeed, about virtually anything.)

A major theme of the Histories is the way in which time can effect surprising changes in the fortunes and reputations of empires, cities, and men; all the more appropriate, then, that Herodotus’ reputation has once again been riding very high. In the academy, his technique, once derided as haphazard, has earned newfound respect, while his popularity among ordinary readers will likely get a boost from the publication of perhaps the most densely annotated, richly illustrated, and user-friendly edition of his Histories ever to appear: “The Landmark Herodotus”, edited by Robert B. Strassler and bristling with appendices, by a phalanx of experts, on everything from the design of Athenian warships to ancient units of liquid measure. (Readers interested in throwing a wine tasting à la grecque will be grateful to know that one amphora was equal to a hundred and forty-four kotyles.)

Modern editors, attracted by the epic war story, have been as likely as not to call the work “The Persian Wars,” but Herodotus himself refers to his text simply as the publication of his historiē—his “research” or “inquiry.” The (to us) familiar-looking word historiē would to Herodotus’ audience have had a vaguely clinical air, coming, as it did, from the vocabulary of the newborn field of natural science. (Not coincidentally, the cradle of this scientific ferment was Ionia, a swath of Greek communities in coastal Asia Minor, just to the north of Halicarnassus, the historian’s birthplace.) The word only came to mean “history” in our sense because of the impact of Herodotus’ text.