Final answer:
Helios rises from, and sets in, the world-encircling river known as Oceanus according to the works of Homer.
Step-by-step explanation:
According to Homer, the world-encircling river from which Helios, the Sun god, rises and sets, is Oceanus. In the time of Homer, the Greeks believed that the Oceanus encircled the flat earth, which was thought of as a disk. This idea echoes throughout Greek mythology and is featured prominently in the works of various Greek poets, including Hesiod and Homer. Oceanus was personified as a Titan and represented the boundary between the known world and the unknown. This mythic depiction serves as a poignant metaphor, encapsulating the Greeks' perception of the known world's confines and the enigmatic mysteries veiled beyond Oceanus's tranquil yet enigmatic waters.