Although sometimes treated as a person (such as Oceanus visiting Prometheus in Aeschylus' "Prometheus Bound", see above) Oceanus is more usually considered to be a place, that is, as the great world-encircling river. Twice Hesiod calls Oceanus "the perfect river" ("τελήεντος ποταμοῖο"), and Homer refers to the "stream of the river Oceanus" ("ποταμοῖο λίπεν ῥόον Ὠκεανοῖο"). Both Hesiod and Homer call Oceanus "backflowing" ("ἀψορρόου"), since, as the great stream encircles the earth, it flows back into itself. Hesiod also calls Oceanus "deep-swirling" ("βαθυδίνης"), while Homer calls him "deep-flowing" ("βαθυρρόου"). Homer says that Oceanus "bounds the Earth", and Oceanus was depicted on the shield of Achilles, encircling its rim, and so also on the shield of Heracles.