An article I found quite interesting.

Before, gods were reigning upon the world. But, several centuries before our era, a handful of greek thinkers broke with this vision of the world. Some, 2,500 years before the big bang theory, even thought of a beginning to the universe.

Philolaus removed the Earth from the center of things.

Anaximander thought nature must have been different before it became what it is today.

In greece, gradually, a shift took place in the way to think about the universe among presocratic thinkers.
Theogonies progressively became cosmogonies but that was also caused by various factors ,among them, the socio-political
and intellectual mutations, the decline of monarchies and the coming of the city, evolving to the democratic political model,
going together with new forms of knowledge like mathematics, writing. Geometry is the paradigm of rationality and it helps elaborate the new political order and it is used to model the world order.
The true grandeur of those speculations is they promote a thought of the becoming (le devenir), of mobility as opposed to fixity (as established once and for all in the struggle of divine powers). Those first cosmologies try to explain how the world formed itself, how it became what it is; they therefore also assume (drastic difference from theogonies) that it will keep on "becoming" and even perhaps die to let room for something else. But this current didn't last and the aristotlean philosophy crushed this by supporting the world's eternity.

Raoul