The best known of all such arrangements is that sometimes called the "Greek Sphere," because those constellations have been preserved to us by Greek astronomers and poets. The earliest complete catalogue of the stars, as thus arranged, that has come down to us was compiled by Claudius Ptolemy, the astronomer of Alexandria, and completed 137 A.D. In this catalogue, each star is described by its place in the supposed figure of the constellation, whilst its celestial latitude and longitude are added, so that we can see with considerable exactness how the astronomers of that time imagined the star figures. The earliest complete description of the constellations, apart from the places of the individual stars, is given in the poem of Aratus of Soli--_The Phenomena_, published about 270 B.C. Were these constellations known to the Hebrews of old? We can answer this question without hesitation in the case of St. Paul. For in his sermon to the Athenians on Mars' Hill, he quotes from the opening verses of this constellation poem of Aratus:-- "God that made the world and all things therein, seeing that He is Lord of heaven and earth, dwelleth not in temples made with hands; neither is worshipped with men's hands, as though He needed anything, seeing He giveth to all life, and breath, and all things; and hath made of one blood all nations of men for to dwell on all the face of the earth, and hath determined the times before appointed, and the bounds of their habitation; that they should seek the Lord, if haply they might feel after Him, and find Him, though He be not far from every one of us: for in Him we live, and move, and have our being; as certain also of your own poets have said, For we are also His offspring." The poem of Aratus begins thus:-- "To God above we dedicate our song; To leave Him unadored, we never dare; For He is present in each busy throng, In every solemn gathering He is there. The sea is His; and His each crowded port; In every place our need of Him we feel; FOR WE HIS OFFSPRING ARE." Aratus, like St. Paul himself, was a native of Cilicia, and had been educated at Athens. His poem on the constellations came, in the opinion of the Greeks, next in honour to the poems of Homer, so that St. Paul's quotation from it appealed to his hearers with special force. The constellations of Ptolemy's catalogue are forty-eight in number. Those of Aratus correspond to them in almost every particular, but one or two minor differences may be marked. According to Ptolemy, the constellations are divided into three sets:--twenty-one northern, twelve in the zodiac, and fifteen southern.