The first philosopher to write down a theory of everything left the gods out entirely

Anaximander, working in Miletus in the 6th century BC, proposed that everything originates from 'the apeiron' — a boundless, indefinite substance — rather than from any familiar element or divine will. It's considered the first recorded attempt to explain the natural world through a single, non-mythological principle.

— Wikipedia contributors, drawing on surviving fragments and Aristotle's later commentary, Anaximander — c. 610–546 BC