sect. iv] DISSERTATION SFXONb. 1^3 



vancement of knowledge ; corning after liim, it was a 9lep 

 backward. 



It is not to his credit as a philosopher to have made this 

 retrograde movement, yet he is not altogether without apo- 

 logy. The physical arguments in favour of the Coperni- 

 can system, founded on the incongruity of supposing the 

 greater body to move round the smaller, might not be sup- 

 posed to have much weight, in an age when the equality of 

 action and reaction was unknown, and when it was not 

 clearly understood that the sun and the planets act at all 

 on one another. The arguments, which seem, in the judg- 

 ment of Tycho, to have balanced the simplicity of the 

 Copernican system, were founded on certain texts of 

 Scripture, and on the difficulty of reconciling the motion 

 of the earth with the sensations which we experience at its 

 surface, or the phenomena which we observe, the same, in 

 all respects, as if the earth were at rest. The experiments 

 and rea^onin^s 01 Galile.r, had not yet instructed men in 

 the inertia of matter te composition of motion ; and 



the followers of Copernicus reasoned on principles which 

 they he' ! in co amoo with their adversaries. A ball, it 

 was said by (he latter, dropt from the mast-head of a ship 

 under saii, does not fall at the foot of the mast, but some- 

 what behind it ; and, in the same manner, a stone, dropt 

 from a high tower, would not fall, on the supposition of the 

 earth's motion, at the bottom of the 'tower, but to the west 

 of it, the earth, during its fall, having gone eastward from 

 under it. The followers of Copernicus were not yet pro- 

 vided with the true answer to this objection, viz. that the 

 ball does actually fall at the bottom of the mast. It was 

 admitted that it must fall behind it, because the ball was 

 no part of the ship, and that the motion forward was not 

 natural, either to the ship or to the ball. The stone, on 

 the other hand, let fall from the top of the tower, was a part 



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