148 THE WORLD MACHINE 



moral of these astonishing measures had come home to them. 

 Their minds, too, had left the inconsequence of earthly concerns 

 in the face of cosmic immensity. 



They had correctly apprehended the character of the 

 " wandering " stars, and had set them in circular or epicyclic 

 orbits, in revolution about the earth and the sun. They do 

 not seem to have computed their relative distances ; but they 

 had enough of an idea of the solar system to make mechanical 

 models of it. 



They knew well the enormous distance of the stars, and they 

 understood clearly that, compared with this distance, the great 

 bulk of the earth was scarce more than a mathematical point. 

 Some among them at least conceived the stars as suns. Sim- 

 plicius, upon what grounds we do not know, stated that some 

 of them were larger than our own. The infinity of worlds was 

 a commonplace to which Lucretius and Cicero refer rather 

 than contend for. 



Through five or six centuries through a far longer time than 

 our modern world has believed in the fact a considerable sect 

 among them, the Pythagoreans and their numerous adherents, 

 taught the motion of the earth upon its axis. Some few among 

 them taught as well the fixity of the sun and the movement of 

 the earth about it. One among them at least had submitted 

 the possible extent of the universe to a mathematical calculation. 



Their insight into the problems of more immediate terrestrial 

 concern was less penetrating. The studies which we now group 

 up under the name of the physical sciences found a much slighter 

 development at their hands. They were metallurgists of long 

 standing ; but of chemical theory they had next to none. Their 

 ideas of heat and other natural forces were of the crudest. They 

 had not deciphered the hieroglyphics of the rocks. Of true 

 conceptions of the age of the earth, or its formation, or of world 

 formation in general, they could have had none at all. 



And yet there were not wanting among them piercing minds 

 which had caught some glimpse of our modern ideas. Zenoph- 

 anes could find evidence of a time when the seas had stood 

 above the tops of the highest mountains. Anaxagoras could 

 look forward to a time when the highest mountains would be 

 again beneath the sea. Empedocles caught distantly the idea 

 of the immutation of the species. In Lucretius' marvellous 

 poem " On Nature " there is a sketch of the struggle for exist- 



