The youngest daughter in the I Ching trigram family is the symbol of The Joyous Lake.
According to Wilhelm:
The Joyous, is autumn, and leads the year toward its fruition and joy. The Joyous acts in the sheep. The Joyous is the lake; it is a sorceress; it is mouth and tongue. It means smashing and breaking apart; it means dropping off and bursting open. Among the kinds of soil it is the hard and salty. It is the concubine.