the same constellations, which is indicative of the importance of these star groups in the eyes of the ancients. Hesiod also refers to the stars Arcturus and Sirius, and these two stars may well be considered the most ancient of all the stars from the standpoint of stellar nomenclature.
Authorities differ as to the source from which the Greek knowledge of the stars was derived, but in all probability it did not come from any one source but was imported from Egypt, Chaldea, and Phoenicia.
The founder of the science of astronomy in Greece was Thales, the head of the Ionic School of Philosophy, a citizen of Miletus, who lived about 540 b.c. It is said that he first taught the Greek navigators to steer by the Little instead of the Great Bear.
Eudoxus, a native of Cnidus, who lived about the fourth century b.c., a contemporary of Plato, was the first Greek who described the constellations with approximate completeness. He is reported to have visited Egypt and to have there received astronomical instruction. He wrote The Enoption, or The Mirror, and The Phenomena or Appearances, both prose works and unfortunately not extant, but Aratos, the Alexandrine poet, versified the latter work about 270 b.c., and it has descended to our day.
Aratos was a native of Soli in Cilicia, and Court Physician to Antigonus Gonatas, King of Macedonia. He was a contemporary of Aristophanes, Aristarchus, and Theocritus, and he always mentions the constellations as of unknown antiquity. His sphere accurately represented the heavens of about 2000 b.c. His poem has been considered an authority on stellar nomenclature, and has been closely followed by all subsequent delineators of the constellation figures.
This sphere of Eudoxus, which has been transmitted to us through the verses of Aratos, contained forty-five constellations, twenty in the northern hemisphere, twelve in the southern, and thirteen in the zodiacal group, the
