Classical elements typically refer to water, earth, fire, air, and (later) aether, which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Usually, aether isn't a common element. Ancient cultures in Greece, Ancient Egypt, Persia, Babylonia, Japan, Tibet, and India had all similar lists, sometimes referring in local languages to "air" as "wind" and the fifth element as "void". The Chinese Wu Xing system lists Wood, Fire, Earth, Metal, and Water, though these are described more as energies or transitions rather than as types of material.