ITS EARLIEST STAGES. 155 



and a considerable part of the science is only the 

 developement and particularization of this general 

 conception. It is not easy to ascertain either the 

 exact method by which the path of the sun among 

 the stars was determined, or the author and date 

 of the discovery. That there is some difficulty in 

 tracing the course of the sun among the stars will 

 be clearly seen, when it is considered that no star 

 can ever be seen at the same time with the sun. 

 If the whole circuit of the sky be divided into 

 twelve parts or signs, it is estimated by Autolycus, 

 the oldest writer on these subjects whose works 

 remain to us 38 , that the stars which occupy one of 

 these parts are obsorbed by the solar rays, so that 

 they cannot be seen. Hence the stars which are 

 seen nearest to the place of the setting and the 

 rising sun in the evening and in the morning, are 

 distant from him by the half of a sign ; the evening 

 stars being to the west, and the morning stars to 

 the east of him. If the observer had previously 

 obtained a knowledge of the places of all the prin- 

 cipal stars, he might in this way determine the 

 position of the sun each night, and thus trace his 

 path in a year. 



In this, or some such way, the sun's path was 

 determined by the early astronomers of Egypt. 

 Thales, who is mentioned as the father of Greek 

 astronomy, probably learnt among the Egyptians 

 the results of such speculations, and introduced 



18 Delamb. A. A. p. xiii. 



