Anaximander 611-547BC
Ionian philosopher

Born in Miletus, Asia Minor, he was successor and perhaps pupil of Thales. He posited that the first principle was not a particular substance like water or air but the 'Boundless' (apeiron), which he conceived of in both physical and theological terms. He is believed to have used the gnomon (a sundial with a vertical rod) to measure the lengths of the seasons, by fixing the times of the equinoxes and solstices, and he is also thought to have drawn the first map of the inhabited world (he recognized that the Earth's surface must be curved, though he visualized it as a cylinder rather than a sphere). No trace of his scientific writings has been found, but he is credited with many imaginative scientific speculations, for example that the Earth is unsupported and at the centre of the universe, that living creatures first existed in the waters of the Earth, and that human beings must have developed from some lower species that more quickly matured into self-sufficiency. He is sometimes called the father of astronomy.