120 GALILEO AND HIS JUDGES. 



his argument, however, on an idea that he had, to the 

 effect that the Copernican system in Galileo's day 

 was " scientifically unlikely:" this, however, is just 

 the reverse of the truth. It was unproved; and, as 

 I have repeatedly said, it is not even now proved to 

 absolute demonstration. 



It is also true that certain most powerful argu- 

 ments for it were not then available, as I shall 

 hereafter have occasion to show at more length ; 

 but it was not scientifically unlikely. Galileo had 

 indirectly damaged the cause by using a certain 

 erroneous argument in its favour; but then his 

 discoveries had simply pulverised the great rival 

 system of Ptolemy, and no astronomer, who knew 

 what he was about, could do otherwise than choose 

 between Copernicus and Tycho Brahe', each of these 

 being of course somewhat modified in detail. Now 

 the theory of Tycho Brahe was a new one, still newer 

 than that of Copernicus, and had all the appearance 

 of a temporary makeshift ; it was not probable that 

 it would receive much approbation in the long run, 

 as in fact it never did. Probability (I mean, of 

 course, in a purely scientific sense) pointed strongly 



system also ; Ptolemy knew that the earth was spherical in its 

 shape, and consequently that what would be above a person in the 

 eastern parts of India, to take an example, would be widely different 

 from that which would be so at the westernmost point of Africa. 

 It may, however, be admitted that an additional cause for 

 bewilderment was presented by the diurnal rotation of the Earth, 

 since it then appeared that the same point in space above you at 

 noon would be far away below you at midnight. 



