For Odysseus and his men, the loss of Helios, the sun, symbolizes a loss of hope.
Tiresias had warned Odysseus about the cattle of Helios, the sun-god. He has warned Odysseus and his men not to disturb or harm the cattle as Harming them will lead to the death of each and everyone. Though Odysseus would remain alive and return home, but alone. He would lose all his men. On the other hand, Odysseus’ men killed the cattle and ate all of them. This instance led Odysseus and his men to think about the loss of hope of returning home.