Within Yoruba aesthetics, the substance of beads themselves has the power to give as well as reflect light. Beads 'mediate light, reflecting, deflecting, transmitting and transforming it in the process.' Beaded double bags are worn by diviners to hold the materials of their profession during sessions with clients. This well-worn diviner's bag arranges the illuminating powers of beads into a design that has no beginning or end, symbolizing both the complexity of the divination process and the light shed on a situation by a skilled diviner. Diviner (babalawo) Kolawole Ositola beginning a divination session. Ijebu-Ode, Nigeria. From Yoruba: Nine Centuries of African Art and Thought by Henry John Drewal and John Pemberton III, 1989, p.21.