Timaeus Nature of the Physical World Purpose of the Universe

http://en.wikipedia.org/wiki/Timaeus_%28dialogue%29#Introduction

Nature of the Physical World
Timaeus begins with a distinction between the physical world, and the eternal world. The physical one is the world which changes and perishes: therefore it is the object of opinion and unreasoned sensation. The eternal one never changes: therefore it is apprehended by reason (28a).




The speeches about the two worlds are conditioned by the different nature of their objects. Indeed, "a description of what is changeless, fixed and clearly intelligible will be changeless and fixed," (29b), while a description of what changes and is likely, will also change and be just likely. "As being is to becoming, so is truth to belief" (29c). Therefore, in a description of the physical world, one "should not look for anything more than a likely story" (29d).



Timaeus suggests that since nothing "becomes or changes" without cause, then the cause of the universe must be a demiurge or a god, a figure Timaeus refers to as the father and maker of the universe. And since the universe is fair, the demiurge must have looked to the eternal model to make it, and not to the perishable one (29a). Hence, using the eternal and perfect world of "forms" or ideals as a template, he set about creating our world, which formerly only existed in a state of disorder.
Purpose of the Universe
Timaeus continues with an explanation of the creation of the universe, which he ascribes to the handiwork of a divine craftsman. The demiurge, being good, wanted there to be as much good as was the world. The demiurge is said to bring order out of substance by imitating an unchanging and eternal model (paradigm). The ananke, often translated as 'necessity', was the only other co-existent element or presence in Plato's cosmogony. Later Platonists clarified that the eternal model existed in the mind of the Demiurge.




(Later in history the term "demiurge" became a term of vilification by Gnostics who purported that the demiurge was a fallen and ignorant god creating a flawed universe, but this was not how Plato was using the term.)