Final answer:
Those who were considered three times perfect, according to ancient Greek philosophy and mythology, ascended to the Isles of the Blessed, a part of the underworld designated for the most virtuous souls who completed the cycle of reincarnation. Poets like Pindar and philosophers including Plato detailed this tripartite afterlife structure.
Step-by-step explanation:
In ancient Greek philosophy and myth, those who achieved a state of perfection through virtuous life and the purification of their souls were believed to ascend to different levels in the afterlife. The concept of a tripartite afterlife structure is discussed in the works of various philosophers including Plato and Pindar, as well as in the Orphic tradition. Plato's dialogues indicate that souls who have purified themselves with philosophy may reach an area 'even more beautiful' and join the gods. Pindar in his Second Olympian Ode describes a vision of the afterlife where those who have completed the cycle of reincarnation and led blameless lives find themselves among the heroes on the Isles of the Blessed.
Following this tradition, Virgil's underworld, as described in his epic poetry, also follows a pattern where afterlife realms correspond with the moral quality of one's earthly life. This can be traced back to the developments beyond Homer's depictions, where moral criteria started to play a significant role in determining one's position in the afterlife. The tripartite structure often involves areas of punishment like Tartarus, places of purification or pleasant time with the gods, and for the most virtuous ones, a special abode with the deities or among heroes as inscribed on the Orphic Gold Leaves.