250 Biographical Acernnt of fA^srt^ 



the other ; and the opposite currents, having no antagonists, 

 become positive in their operation upon the bodies, and produce 

 a constant motion in them towards each other. And we shall 

 find, by considering the circumstances under which these bodies 

 are placed, and the supposed nature of the fluid, that this motion 

 must be uniformly accelerated, and in the inverse ratio of the 

 square of the distance, as all the forces are which are conceived 

 to depend upon the Newtonian attraction. 



If bodies were all equal in the quantity of matter which they 

 contained, or if the quantity of matter was always in proportion 

 to their bulk, their attraction would be in the same proportion. 

 The quantities of matter are, however, unequal in proportion to 

 their bulk ; and if we suppose that the gravific fluid can pass 

 through the pores of bodies, and that it is only stopped by the 

 actual particles which they contain, we shall find that a body 

 must always intercept a number of the atoms exactly in propor- 

 tion to the number of its particles, or that the attraction of 

 bodies must be in proportion to the quantity of matter which they 

 contain. Hence we arrive at the explanation of the great law, 

 that the power with which bodies attract each other, or to use 

 Le Sage's expression, with which they are impelled towards each 

 other, is in the direct ratio of the quantity of matter, and the 

 inverse ratio of the distance. This may be regarded as the 

 essential fact of Le Sage's theory, the base upon which he 

 attempted to erect the grand edifice, and the master key with 

 which he proposed to unlock the secret recesses of nature's 

 operations. 



In considering any theory of this description, the first ques- 

 tion that we ought to ask is, whether we have any actual 

 evidence of its truth ; whether there be any positive fact, or any 

 independent phenomenon, which can really lead us to conclude 

 that this gravific fluid exists ? To this question we are obliged 

 to answer in the negative; it is not the object of any of our 

 senses, and, in short, there is nothing which in any way indicates 

 its presence, or announces its existence. We are then to regard 

 it simply as an hypothetical body, called in to explain a set of 

 phenomena ; and here, then, two new questions present them- 

 selves : Does it explain all the phenomena? and does it in 

 any degree tend to generalize them, or to reduce them to a form 

 which is more consonant to the ordinary operations of nature ? 

 If it fail in the first of these respects, it is palpably false ; if in 

 the second, it is useless. As far as we are able to judge of the 

 theory, it will be found to be correct in ail its applications, and, 

 therefore, is not to be rejected on the first account ; but the 

 question of utility is, perhaps, more doubtful. On the subject 

 of generalization there are two main points which Le Sage pro- 

 fesses to have accomplished ; first, to reduce all the motions of 

 attraction and repulsion to the influence of one agent, or to show 

 that they are exactly reducible to the same laws ; and, secondly, 



