Orality: the way in which information spreads through (predominantly) illiterate societies. The study of oral literature has helped classicists and historians to evaluate the origins of their information.
In the early twentieth century, scholars studying the formal characteristics of ancient texts, recognized that myth, fairy tales, and other popular stories share certain characteristics, recurring motifs, and stock phrases, which can also be found in other texts. This made it possible to re-evaluate old interpretations. For example, Herodotus’ story that the Median capital Ecbatana had been a city with seven increasingly high concentric wallsnote[Herodotus, Histories 1.98.] had been explained as an imperfect account of a ziggurat, but could now identified as a motif from a fairy tale.
Many ancient stories have been recognized as originating in an oral tradition. This does not necessarily mean that they are untrue, but gives pause for thought. For example, when we read that the Athenian leader Pisistratus twice attempted a coup d’état and succeeded the third time, we must recognize that “third time lucky” is a standard motif. Of course Pisistratus’ tyranny is a historical fact, but the story of his accession is suspicious and cannot immediately be accepted as true.
By the mid-twentieth century, it was already obvious that written sources like Herodotus’ Histories and the Bible are essentially islands in a sea of orally transmitted stories. This was later confirmed by linguists, who established that the patterns of spoken language are present in certain stories.
Of course, the similarities between ancient stories had already been recognized before. Plutarch’s story about the death of the great god Pan has parallels in half a dozen other cultures. The basket that carried Sargon of Akkad down the Euphrates, carried Moses down the Nile, and Romulus and Remus down the Tiber. The island-shaped fish of the Irish saint Brendan resurfaced to create problems for Sinbad the Sailor. The motif of gods visiting the earth prior to the destruction of a sinful city is the background to Genesisnote[Genesis 18.1-19.29] and Ovid's story of Philemon and Baucis.
Borrowings can be quite profound. The Babylonian Creation Epic may well have influenced the philosophy of Thalesnote[Walter Burkert, "Oriental Wisdom Literature and Cosmogony", in: Babylon, Memphis, Persepolis. Eastern Contexts of Greek Culture (2004) 49-70.] while eastern roots have been suggested for the Olympic Games.note[D. Chibo, "The Mesopotamian origins of the Olympic Games", in: Nikephoros 20 (2007).] There must have been a true ocean of oral information, which we can only fathom when we have written sources. These sources are, in fact, atypical of the information that must have been around everywhere. We must always remain critical: our written texts are not representative of the information that used to be around, precisely because they are written texts.