Milesians. Pre-Socratic, named for Miletus on Asia Minor coast across from Greece, 6th cent. BC. Thales, Anaximander, Anaximenes.
Anaximenes takes air to be the basic material stuff, while earth, fire, and water are formed out of it by condensation and rarefaction: fire is the least dense; air is denser than fire, water denser than air, and earth the most dense.
Anaximander takes the infinite or the indefinite (apeiron) to be the basic material stuff
Thales (some call him the first philosopher), he thought water was the basic stuff of nature.
Two Strikes 