Atoms, as is well known, were originated by Democritus to fend off Parmenides' challenge of an unchangeable, eternal one.
The other large category of thought in modern physics is that of the wave. Where did this originate? Should we hazard Thales, who said all was water? Do waves ripple on the liquid surface of being? One common understanding of Thales' thought is that water is an originary principle, which possibly ties it in with Egyptian and Hebrew creation myths. But another angle of thought shows that water takes up the shape of any vessel into which water is poured. What if that vessel were the shape of a pebble, or the shape of a man? Or indeed the shape of a universe?
Or should we hazard that the whole school elaborated this thought - the Miletus School with Anaximander, who subtracted the specificity of water to come up with a preconception of substance - being without quality, and Anaximenes who instead posited air, and a process of rarefaction and condensation.