Sentence:  Aristotleians assumed that rest is the natural state of a body in the terrestrial sphere. If something moves, then this unnatural change in its state requires explanation. Something must be pushing on it, or its motions must derive from some internal teleological "drive" within it – a sort of simple consciousness motivating it. These internal drives were called "<WSD>entelechies</WSD>," and Aristotleians held that the entire universe is imbued with <WSD>entelechies</WSD>. 
Meaning of the word marked with <WSD> tags:  The complete realisation and final form of some potential concept or function; the conditions under which a potential thing becomes actualized.