Timaeus

A dialogue that is mostly one long speech on the origin and structure of the universe. It opens with a recap of an ideal city and with Critias' story, heard from Solon, of ancient Athens defeating the island power of Atlantis. Then Timaeus, an astronomer, gives what he calls only a likely account of the cosmos. A good divine craftsman, the Demiurge, looks to an eternal model and makes the world as a single living being with a body and a soul, ordered by mathematical proportion. Time is made as a moving image of eternity. The four elements are built from geometrical triangles that form regular solids, and everything comes to be in a receptacle that Timaeus calls the nurse of becoming. The final part turns to the human body, perception, the mortal parts of the soul, disease and health.

It was the most widely read Platonic dialogue for over a thousand years, and it remains the founding text for ideas of a designed, mathematically ordered cosmos.