'Robes,' as in Revelation 7, signify truths of defense. Before they were washed they signified falsities. People in falsities from ignorance in the spiritual world appear first in obscure garments of various colors, and while they are in temptations, they appear in filthy garments. When they come out of temptations, they appear in 'white robes and clean' because of their purification from falsities.

(References: Apocalypse Explained 475)