the vast majority of them came from reknown intellectual centers of the Greek world like Cyrene, Kos, Cnidos, Samos, Rhodes, Byzantion, which politically were connected to Ptolemaic interests, through intensive diplomatic relations, possessions or spheres of influences. We should mention some of them from different fields: Euclide, Eratosthnes, and Eudoxis of Cnidos in mathematics; Archimides in applied science; Calimachus, Apolonius of Rhodes, Aristophanes of Byzantion in literature; Praxagoras of Kos in medicine. Ctesibios of Alexandria was one of the most important scientists during the heyday of the Library, who is credited with a number of ingenious inventions, including an improved device of the waterclock. A detailed description of his work is given by Vitruvius (1st cent. AD) in his invaluable manual “De Architectura”. Vitruvius speaks of more than one model; the final version was based on the inflow klepsydra type. This was a case of cultural interaction, since Ctesibios based his research on the older Egyptian outflow and the modified inflow clocks, and that he realized their defects and came up with definite improvements. Another area of interaction was in medicine, a field that both Egypt and Greece had long established traditions and achievements. The coexistence of the two, Greek and Egyptian traditions in Hellenistic Alexandria led to a remarkable progress in Medical learning with impressive achievements. Herophilus, the leading Alexandrian physician and his school directed their science toward a “scientific medicine”, in contrast to the classified mass of physical observation and disease descriptions of the Coan school of Hippocrates . In order to achieve this, Herophilus embarked on a new study of the human body based on anatomy and human dissection. His new approach had never been practiced in classical Greece. It is probable that Herophilus had benefitted from the Egyptian practice of mummification. Another breakthrough was definitely achieved in the field of neurology and the function of the brain as a result of Herophilus’ anatomy of the nervous system. He was able to prove that the brain was the seat of intelligence and not the heart as Aristotle among others had thought.48 Aristarchus of Samos lived and conducted his research in Alexandria early in the 3rd century BC (Fig. 52). He applied himself to the task of reviving the entire study of the cosmic system. The prevailing paradigm in all antiquity (and throughout the Middle Ages) was that the earth was stable and fixed at the center of the universe. This was a kind of an idée fixe which had been adopted and supported by Plato and Aristotle, and by the great astronomer Eudoxus of Knidos who was followed by Archmides, Hipparchus, Strabo and Claudius Ptolemy and their followers in Islam and
Rufus, 1889, 71-4; Cf. Fraser, 1972, 512, nn. 96-7.