The Yoruba – being a large, complex society – is sedentary, agriculturist and hierarchical. They are ruled by hereditary kings known as Obas, and their access to the supernatural world is supervised by a very complex arrangement of priests (i.e. Olowa) and spiritual intermediaries. Their cosmology is arranged in terms of the tangible realm of the living (aye) and the invisible realm of the spirits and the hereafter (orun). Their relationship is sometimes described as being that of a gourd with tightly-interlocking upper and lower halves, or as a divination board with a raised rim and a depressed centre. The creator of the world is Olodumare (or Odumare, Olorun, Eleda or Eleemi, depending on the area), who is the source of all ase – life force. Orun is populated by all manner of spirits (iwin, ajogun, egbe and oro), gods (orisa) and ancestors (ara orun), all of whom influence the living. They can all be reached, appealed to or appeased through human intermediaries such as the babalawo (diviner). Most Yoruban artistic heritage is designed to thwart evil spirits, and to placate or honour those that bring good fortune to the populace. - (LA.576)