Anaximander

Anaximander of Miletus (c. 610–546 BCE) was an Ionian natural philosopher, a pupil or associate of Thales according to later tradition. He is credited with proposing the apeiron, the boundless or indefinite, as the first principle of all things, and with early models of the earth, the heavens, and the cosmos. Herodotus and later writers attribute to him the introduction of the gnomon, and a world map is also ascribed to him. He wrote a prose treatise, On Nature, of which only one brief sentence survives verbatim, preserved by Simplicius.