According to the Lamba people of Zambia, there is a great lake of water above the dome of the sky. This lake is held back by a weir protected by guardians appointed by Lesa (God). Sometimes Lesa appoints children to guard it, and their irresponsible playing makes holes in the weir and allow the water to spill to earth as rain. When Lesa appoints grown men to guard the weir, then there is no rain.
Lightning (akampeshimpeshi) is caused by the guardians of the weir swinging and tossing their knives (imyele). The knives do not fall – if they did, the earth would be destroyed.