In order to explain the origin of things and the nature of change and motion, the philosophers in Miletus sought to discover or describe one primary, material substance as the base of all natural objects and the source of all motion. Thales was an astronom, mathematician, and philosopher, the first natural philosopher in the Milesian School. Thales postulated that this primary substance was water. Important philosophers in this region were Thales, Anaksimandros, Anaksimenes, Hekataios, etc..