[2] According to Plutarch, Ephorus declined Alexander the Great's offer to join him on his Persian campaign as the official historiographer.
The whole work, edited by his son Demophilus—who added a 30th book—contained a summary description of the Sacred Wars, along with other narratives from the days of the Heraclids up until the taking of Perinthus in 340 BC by Philip of Macedon, covering a time span of more than seven hundred years.
These writings are generally believed to be the main or sole source for Diodorus Siculus' account of the history of Greece between 480 and 340 BC, which is one of only two continuous narratives of this period that survive.
[9] Polybius, while crediting him with a knowledge of the conditions of naval warfare, ridiculed his description of the 362 BCE Battle of Mantinea as showing ignorance of the nature of land operations.
Besides the universal history, Ephorus wrote an Epichorios logos (Ἐπιχώριος λόγος), a patriotic essay in which he praised the traditions of Cyme.
According to the Encyclopædia Britannica Eleventh Edition, his surviving writings all show a certain lack of passion, in spite of his keen interest in matters of style, and of political partisanship, except for his enthusiasm for Cyme.
[12] He was commended for drawing (though not always) a sharp line of demarcation between the mythical and historical;[13] he even recognized that a profusion of detail, though lending corroborative force to accounts of recent events, is ground for suspicion, in reports of far-distant history.