62 GALILEO AND HIS JUDGES. 



vations, especially with the imperfect instruments 

 then in use ; I say sufficiently, because that there 

 were such errors he knew, and he insists on the fact 

 in the Dialogue. 



Much discourse is spent on the distance of this 

 new star ; the apparent reason of which is that it 

 had created some sensation among the astronomers 

 of that day, and therefore the subject received an 

 attention out of proportion to its real importance 

 I mean importance so far as the Copernican con- 

 troversy was concerned. 



The conversation is then brought back to the 

 objections made by contemporary philosophers to the 

 Copernican system. Aristotle's idea of the universe 

 was that of a vast sphere, or number of concentric 

 hollow spheres, with the Earth in the centre ; if that 

 were shown to be probably untrue, his system broke 

 down.* Coming, however, to our own immediate 

 portion of the universe, the question is now raised 

 whether the Earth or the Sun is the centre of revo- 

 lution. Galileo, by the mouth of Salviati, explains 

 forcibly the argument for the Sun being so. That 

 Mercury and Venus revolve round the Sun he takes 

 for certain ; the phases of Venus, which he had 



* It is curious that the notion of the universe being shaped as a 

 curve returning into itself has been started by some modern Ger- 

 man philosophers, founders of what has been called " non-Euclidian 

 geometry." The investigations of astronomers, however, rather 

 point to the conclusion that the stellar universe has no centre, no 

 symmetrical figure, though speculations such as these must always 

 be uncertain. 



