That which initiates motion, but which is itself unmoved. The first of the Five Ways of Aquinas argues for such an entity. It may seem as though this is a version of the first cause argument, with God seeming like the railway engine that starts the shunting of connected waggons. But in the Aristotelian and medieval tradition the argument is different. Nature, for the Greeks, is characterized by a nisus or tendency to actuate what is potential; change is driven by a kind of striving or direction towards a goal; an ethical action at a distance. The process of change or becoming is intelligible only if the goal acts in the world; it is the initiator of motion because it is the final cause of it. The idea is that a natural motion, such as that of the iron filings towards the magnet, is analogous to the impulses of agents (thus, we still speak in one breath of the filings being drawn towards the magnet, and the man being drawn to the woman). The single unmoved mover is the one thing that has a self-contained activity (self-consciousness) of its own, and that is not therefore caused to move by the need to actualize any potential. It is in some way identical with the forms that it thinks, and the movements of nature are inspired by the things of nature being drawn towards it. Thus the primum mobile or outermost sphere of the heavens best imitates the self-contained nature of God by its perfect, spherical rotation. In this system it is, literally, love that makes the world go round. Unfortunately however the unmoved mover, being entirely wrapped up in itself, cannot act in the world, nor possess any awareness of it, and this aspect of the doctrine was formally condemned in 1277. See also Neoplatonism.