60 GALILEO AND HIS JUDGES. 



doubt, many were employed at that time on both 

 sides ; I think it was the late Professor de Morgan 

 who (in an article written for a popular periodical) 

 made a list of these ; and it must in all fairness 

 be said, that this circumstance ought to be taken 

 into account, as palliating the apparent obstinacy 

 of the anti-Copernican party in denying the motion 

 of the Earth. The argument drawn from the tides is, 

 of course, the most striking instance of these scientific 

 fallacies ; but it was by no means the only one ; 

 in this particular dialogue there is another, which 

 is worth noticing because it confirms what I have 

 just said as to Galileo knowing nothing of the 

 doctrine of universal gravitation. He puts into the 

 mouth of Salviati the argument that bodies which 

 emit light, as do the Sun and fixed stars, are essen- 

 tially different from those which, like the Earth and 

 planets, have no such property a distinction which 

 modern astronomy does not endorse and that, as 

 the Earth in this respect resembles the planets, and 

 the planets are undoubtedly moving, so probably 

 the Earth also is like them in motion, whilst the 

 Sun and the stars remain at rest. It is obvious 

 that ideas of this kind, however plausible they may 

 seem, are utterly at variance with the theory of 

 universal gravitation, according to which, even if 

 the Sun were a dark, cold body and the Earth glowing 

 with heat and light, the Earth would revolve about 

 the Sun just as it does now, provided the, mass of 

 the two bodies remained the same as at present. 



