SIGHT AND SEEING IN ANCIENT TIMES 417 



because the people would have no place to go when it began to decrease. 

 What an immense amount of speculation and calculation the Ptolemaic 

 system made for the astronomers ! The philosophers all agreed with 

 Pliny that ' with the mind we see, with the mind we discriminate ' ; 

 but unfortunately they too often forgot that the mind can not dis- 

 criminate unless the senses have correctly furnished the facts. So far 

 as sight is concerned, this is strikingly exemplified in all the work of 

 the well-known mathematician, Euclid. As he knew nothing about 

 refraction and had no rational theory of light, he had recourse to phi- 

 losophy to provide him with a basis for his work on optics, but which 

 is really a treatise on perspective. So far as is now known, the 

 first man who made a study of refraction was Posidonius, who lived 

 nearly two centuries after the father of geometry. He illustrated the 

 principle by the familiar experiment of placing a coin on the bottom 

 of an empty vessel in such a way that it was not visible because of the 

 intervening rim, then bringing it into sight by filling the vessel with 

 water. 



The ancients were almost entirely without apparatus and had no 

 instruments of precision; in fact, very few of them had any interest 

 in the mechanic arts. Though Thales foretold an eclipse of the sun 

 as early as B.C. 600, neither the Greeks nor the Romans had any 

 way of measuring time that was even approximately accurate. Under 

 the republic the normal Roman year contained only three hundred and 

 fifty-five days. Julius Csesar very nearly corrected the error, although 

 in the time of Pope Gregory XIII., the year had become eleven days 

 too long. It has ceased to be a matter of controversy whether the 

 christian era is four years too short. There is hardly any doubt that 

 the authors of the Homeric Poems had a very undeveloped color-sense. 

 It is highly probable that two or three millenniums ago the countries 

 about the Midland Sea, especially the iEgean, displayed to the ap- 

 preciative beholder many glorious landscapes which the destruction of 

 the forests and the drying up of the perennial streams have completely 

 obliterated. Not a few streams that formerly flowed all the year round 

 have become temporary torrents, more baneful than beneficent in their 

 effects or beautiful to behold. Many hills that were once covered with 

 natural vegetation now present a parched and barren appearance. In 

 the Homeric Poems we find epithets not a few that felicitously de- 

 scribe natural objects, or at least characterize them, but they are 

 the result of a happy instinct rather than a careful observation. In 

 the long ' Hymn to Demeter/ not many lines are given to an enumera- 

 tion of the flowers that spring so profusely from the bosom of the earth. 

 The treatment of the subject is perfunctory and superficial. In the 

 much shorter ' Hymn to the Earth, the Mother of All,' flowers are 

 barely mentioned and not particularized. In the brilliant descrip- 



VOL. LXX. — 27 



