Cosmology comes from the Greek word kosmos which, according to the Shorter Oxford English Dictionary means ‘the world or universe as an ordered system’ or ‘order, harmony, a harmonious system’. Cosmology then, means the theory of the universe as an ordered whole, and of the general laws which govern it. In philosophy, it is taken to mean that part of metaphysics which deals with the idea of the world as a totality of all phenomena in space and time. According to Greek thought, cosmos came out of chaos-‘the formless void: a state of utter confusion and disorder’—by differentiating the various elements. The concept is often associated with cosmogony, ‘a theory, system, or account of the generation of the universe’.