When one man said, then, that reason was present - as in animals, so throughoutWithout doubt, the idea became influential as a result of Aristotle. He argues (in Book 12 of the Metaphysics) that the world is moved by an eternal prime mover who is the source of all process and change, while not itself subject to process or change. This substance does what is the highest form of life ought to do, namely to think. ‘The rule of many is not good; one ruler let there be.’ Thomas Aquinas finally unified Catholic and ancient Greek with this idea at its centre.
nature - as the cause of order and of all arrangement, he seemed like a sober
man in contrast with the random talk of his predecessors. We know that
Anaxagoras certainly adopted these views, but Hermotimus of Clazomenae is
credited with expressing them earlier. Those who thought thus stated that there
is a principle of things which is at the same time the cause of beauty, and that
sort of cause from which things acquire movement. [Metaphysics book I, 984b18
Sed pluralitas principatuum non est bonum. Sicut non esset bonum quod essent
diversae familiae in una domo, quae invicem non communicarent. Unde relinquitur
quod totum universum est sicut unus principatus et unum regnum. Et ita oportet
quod ordinetur ab uno gubernatore. Et hoc est quod concludit, quod est unus
princeps totius universi, scilicet primum movens, et primum intelligibile, et
primum bonum, quod supra dixit Deum, qui est benedictus in saecula saeculorum.
Amen. [Commentary on the Metaphysics, book 12]
*Note (quick advertisement for the Logic Museum) that the Museum is still, AFAIK, the only place on the internet where you can link to Aristotle via Bekker numbers. The coverage and scope of Aristotle, and the medieval writers who cited his work, is increasing all the time.