Lethe, the goddess of forgetfulness, was mentioned by hesiod, a Greek poet in the 8th century BC, in her work The Divine Spectrum, and she was one of the daughters of Eris, the goddess of disputes.
Hesiod also mentioned Lupe, the goddess of sadness, who is one of the daughters of Eris and one of the three sisters of pain and sadness, representing sadness.
Ghosts and gods don't know which one you mean. There are many gods and ghosts. Goddess' words include Persephone and Hecate. There are many versions of this god. Some people say that she saved Persephone, and some people say that Demeter, the goddess of harvest, is a trinity god (Persephone represents the middle maturity and Hecate represents the final harvest).