104 On the Doctrine that the Phenomena of Terrestrial 
sary opposition to his system. At the same time there is a la- 
tent, though popular error, in confounding physics and geometry, 
for all physical effects result from competent proximate causes, 
often varying ; and all geometrical laws result from relations, 
always fixed. But, if our excellent philosopher so well accounted 
for the phenomena of the solar system by geometry, founded on 
the basis of an occult principle, with how much more satisfaction 
would he have done it on a mechanical basis! The author of 
this hypothesis has caleulated, however,.on no change but in 
nomenclature. 
VIII. It is asserted, that as gravitation is a fiat of Omnipo- 
tence, so to altempt to account for it is beyond the due bounds of 
philosophical inquiry. 
Without intending any personal disrespect to those who have 
used this argument, it may be asserted, that such has been the 
prejudice of ignorance from the age in which man first used a 
Spade to augment the natural productions of the earth, to the 
days of Galileo, and even to our time, when Jenner discovered 
the means of extirpating a fatal disease. Shall we more nearly 
approach the CAUSE OF CAUsES in determining the mechanism, 
by which a planet is held together, or by which a systein moves, 
than by investigating the circulation of the blood, or by the che~ 
mical analysis of any substance in Nature? The causes of mo- 
tion would still remain behind; and, were a future age to discover, 
these, the prime mover of all things, the sublime and incompre- 
hensible Creator and Preserver, would still be at an infinite di- 
stance from the finite powers of man. 
IX. It is asserted that the law of gravitation is not proved 
to be the law of motion. 
To prove the affirmative of this proposition was, however, the 
entire business of the * Principia’’ of Newton, and has been the 
employment of all mathematicians from his time to our own. If 
the laws of motion are not the laws of gravitation, then have 
philosophers been dicaming during the last hundred years. Lf 
merely identify what they have proved; and, as mathematicians 
have, by the hypothesis of gravitation, proved the laws of mo- 
tion, | now desire to discard the unknown or assumed quantity, 
and to restore the known motions of Nature in its place—for 
the purpose of explaining the modus operandi by which the 
phznomena are produced. 
It is imagined that I had forgotten the relations of radii and 
circles; I was not, however, alluding to circles, but to the sur- 
faces of concentric spheres, which were the objects of discussion, 
and which are to each other as the squares of their radii. The 
spaces generated on spherical surfaces being to eaeh other as 
the squares of their radii, it follows that the quandities of motion 
) generated 
