SEQUEL TO COPERNICUS. 287 



.0 get rid of the difficulty by merely denouncing the new tenets as 

 inconsistent with religious belief,- and by visiting the promulgators of 

 them with severity such as the state of opinions and institutions may 

 allow. The prosecutors of Galileo are still up to the scorn and aver- 

 sion of mankind : although, as we have seen, they did not act till it 

 seemed that their position compelled them to do so, and then pro- 

 ceeded with all the gentleness and moderation which were compatible' 

 with judicial forms. 



Sect. 5. The Heliocentric Theory confirmed on Physical considera- 

 tions. (Prelude to Kepler's Astronomical Discoveries.) 



BY physical views, I mean, as I have already said, those which de- 

 pend on the causes of the motions of matter, as, for instance, the con- 

 sideration of the nature and laws of the force by which bodies fall 

 downwards. Such considerations were necessarily and immediately 

 brought under notice by the examination of the Copernican theory ; 

 but the loose and inaccurate notions which prevailed respecting the 

 nature and laws of force, prevented, for some time, all distinct reason- 

 ing on this subject, and gave truth little advantage over error. The 

 formation of a new Science, the Science of Motion and its Causes, was 

 requisite, before the heliocentric system could have justice done it with 

 regard to this part of the subject. 



This discussion was at first carried on, as was to be expected, in 

 terms of the received, that is, the Aristotelian doctrines. Thus, Coper- 

 nicus says that terrestrial things appear to be at rest when they have 

 a motion according to nature, that is, a circular motion ; and ascend 

 or descend when they have, in addition to this, a rectilinear motion by 

 which they endeaver to get into their own place. But his disciples 

 soon began to question the Aristotelian dogmas, and to seek for sounder 

 views by the use of their own reason. " The great argument against 

 this system," says Msestlin, "is that heavy bodies are said to move 

 to the centre of the universe, and light bodies from the centre. But 

 I would ask, where do we get this experience of heavy and light 

 bodies ? and how is our knowledge on these subjects extended so far 

 that we can reason with certainty concerning the centre of the whole 

 universe ? Is not the only residence and home of all the things which 

 are heavy and light to us, the earth and the air which surrounds it ? 

 and what is the earth and the ambient air, with respect to the im- 

 mensity of the universe ? It is a point, a punctule, or something, if 

 there be any thing, still less. As our light and heavy bodies tend tc 



