Our sample today comes from Diodorus Siculus' Library (3.13), where the historian describes the earlier work of Hecataeus of Abdera on a mysterious land far to the north:
"Hecataeus and some others have said that on the coasts opposite the Celtae, there is an island little less than Sicily, under the Arctic Pole, where they who are called Hyperboreans inhabit. They say that this island is exceedingly good and fertile, bearing fruit (i.e., crops of grass) twice a year. The men of the island are, as it were, priests of Apollo, daily singing his hymns and praises, and highly honouring him. They say, moreover, that in it there is a great forest, and a goodly temple of Apollo, which is round and beautified with many rich gifts and ornaments; as also a city sacred to him, whereof the most part of the inhabitants are harpers, and play continually on their harps in the temple, chanting hymns to the praise of Apollo, and magnifying his acts in their songs." (trans. H. Cogan)
Many modern historians believe this passage represents a description of Britain, with the round temple being Stonehenge on Salisbury Plain. If so, this would be a remarkable piece of literature, since Hecataeus lived in 300 BCE, roughly a thousand years after Stonehenge's heyday. (Not all archaeologists agree, however.) But if we adopt the ancient astronaut theorists' textual literalism, we are prevented from investigating the question of whether this passage refers in fact to Britain and Stonehenge because, since we must take this literally, we should be looking for an island the size of Sicily near the North Pole. An alien Arctic research station? Was the temple a biodome?
I don't think it would surprise anyone to know that there is no such island at the North Pole (it's water up there under the ice), or that there has been no weather warm enough to grow two rounds of annual crops since humans evolved. This line of investigation is stale. But if ancient astronaut theorists choose not to interpret this text literally, then we must ask what criteria they use to decide which texts are worthy of literal readings, and which must be read symbolically or figuratively?
Of course, this is a moot point for ancient astronaut theorists, since textual literalism means they also have to accept that Geoffrey of Monmouth was literally correct that the stones of Stonehenge were meant as a bathtub for African giants: "The giants of old brought them [the stones] from the farthest coasts of Africa [...] Their design in this was to make baths in them, when they should be taken with any illness" (Historia Regum Britanniae 8.11, trans. A. Thompson and J. A. Giles). And, oh yeah, Stonehenge's stones aren't African either. Oops.
Just remember that bit of "ancient text" the next time an ancient astronaut theorist tries to tell you that Stonehenge is "obviously" a "UFO command center."