What metaphors are used in Ghosts by Henrik Ibsen?

Oswald's big speech about the "joy and openness of life" uses the sun as its central metaphor; the light that reveals tells the truth how impossible it is for Mrs. Alving to atone for her guilt has its source in the flames of the burning orphanage; and, finally, it is the sun, the source of all light, that reveals the meaning of the play's completed action.