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whole , they form the first philosophical grouping 62 , although decidedly not a single philosophical school , as there are very great differences in their systems of thought , even to the point of being diametrical opposites on individual topics 63 . A further difference is that their foci of interests varied greatly , and geographically they were also disparate , extending from Miletus , in the east , in what is now Turkey , to Iona , on the coast of modern Italy , in the west .
Despite coming to very different conclusions to each other , there are nevertheless clearly defined themes in common . All were interested in the ultimate nature of matter , and most were intrigued by the possibility that some of what we see – perhaps all of it - may be an illusion . Another shared theme is an interest in cosmology , i . e . the origin and development of the universe , which has only been considered part of physics since around the beginning of the twentieth century .
Thales lived and worked in Miletus around the first half of the Sixth Century BCE . In common with Anaximander and Anaximenes , his focus of professional interest were questions concerning the processes by which matter appears to change its properties , whether there is a ‘ foundational ’ state of matter from which all other forms result , and , if so , the nature of this fundamental material .
For Thales , water is the original substance . This may seem odd to Twenty-first century minds living in an era of nuclear physics , but it is not as strange as it at first appears . Water as ice is solid , melts to form a liquid , and this turns to a gas – steam – when heated further , thus representing the three familiar forms of matter – solid , liquid and gas - central to modern physical sciences . The fourth state of matter here – plasma – was of course unknown at that time .
Pythagoras was also a Presocratic philosopher : based initially in Samos ( in what is now Turkey ), he later practised in Croton , now part of southern Italy . He concurred with Thales regarding the fundamental nature of water . Although far better known than most of the Presocratics , it is nevertheless true that Pythagoras left no written record of his work , and crucially , neither did a succession of his followers . Consequently , although little of Thales ’ and Pherecydes ’ work has survived , what information we have is far more reliable and , relatively speaking , a very much greater quantity . For example , in the case of Pherecydes , around 100
62
Waterfield 2000 , p . xii
63
Sambursky 1956 , p . 4