Analysis of information sources in references of the Wikipedia article "Unmoved mover" in English language version.
The universe has no beginning in time, no temporal first cause, so Aristotle is obviously not seeking an efficient cause in the sense of "what set it all off?" Aristotle's unmoved mover acts as final cause, as the good toward which all things strive. That is, it acts an objects of desire: "The object of desire and the object of thought move without being moved" (Met., 1072a26–27).
{{cite web}}: CS1 maint: multiple names: authors list (link)In Metaphysics 12.8, Aristotle opts for both the uniqueness and the plurality of the unmoved celestial movers. Each celestial sphere possesses the unmoved mover of its own—presumably as the object of its striving, see Metaphysics 12.6—whereas the mover of the outermost celestial sphere, which carries with its diurnal rotation the fixed stars, being the first of the series of unmoved movers also guarantees the unity and uniqueness of the universe.