Page "Phaedrus (dialogue)" Paragraph 30

As souls are immortal, those lacking bodies patrol all of heaven so long as their wings are in perfect condition.

When a soul sheds its wings, it comes to earth and takes on an earthly body which then seems to move itself. These wings lift up heavy things to where the gods dwell, and are nourished and grow in the presence of the wisdom, goodness, and beauty of the divine.

However, foulness and ugliness make the wings shrink and disappear.