NATURAL PHILOSOPHY. 181 



particle A or B were by itself, it could not gravitate, that is, it could hare 

 no attraction, no force of gravity. Supposing A to exist in that isolated 

 state and without gravitating force, and then B placed in relation to it, 

 gravitation comes on, as is supposed, on the part of both. Now, without 

 trying to imagine how B, which had no gravitating force, can raise up grav- 

 itating force in A; and how A, equally without force beforehand, can raise 

 up force in B, still, to imagine it as a fact done, is to admit a creation of 

 force in both particles ; and so to bring ourselves within the impossible con- 

 sequences which have already been referred to. 



It may be said we cannot have an idea of one particle by itself, and so the 

 reasoning fails. For my part I can comprehend a particle by itself just as 

 easily as many particles ; and though I cannot conceive the relation of a 

 lone particle to gravitation, according to the limited view which is at present 

 taken of that force, I can conceive its relation to something which -causes 

 gravitation, and with which, whether the particle is alone, or one of a uni- 

 verse of other particles, it is always related. But the reasoning upon a lone 

 particle does not fail ; for as the particles can be separated, we can easily 

 conceive of the particle B being removed to an infinite distance from A, and 

 then the power in A will be infinitely diminished. Such removal of B will 

 be as if it were annihilated in regard to A, and the force in A will be annihi- 

 lated at the same time; so that the case of a lone particle and that were dif- 

 ferent distances only are considered become one, being identical with each 

 other in their consequences. And as removal of B to an infinite distance is 

 as regards A annihilation of B, so removal to the smallest degree is, in prin- 

 ciple, the same thing with displacement through infinite space ; the smallest 

 increase in distance involves annihilation of power ; the annihilation of the 

 second particle, so as to haA-e A alone, involves no other consequence in re- 

 lation to gravity; there is difference in degree, but no difference in the 

 character of the result. 



It seems hardly necessary to observe, that the same line of thought grows 

 up in the mind, if we consider the mutual gravitating action of one particle 

 and many. The particle A will attract the particle B at the distance of a 

 mile with a certain degree of force ; it will attract a particle C at the same 

 distance of a mile with a power equal to that by which it attracts B ; if 

 myriads of like particles be placed at the given distance of a mile, A will 

 attract each with equal force ; and if other particles be accumulated round 

 it, within and without the sphere of two miles diameter, it will attract them 

 all with a force varying inversely with the square of the distance. How are 

 we to conceive of this force growing up in A to a million fold or more, and 

 if the surrounding particles be then removed, of its diminution in an equal 

 degree "? Or, how arc we to look upon the power raised up in all these outer 

 particles by the action of A on them, or by their action one on another, 

 without admitting, according to the limited definition of gravitation, the 

 facile generation and annihilation of force ? 



The assumption which we make for the time with regard to the nature of 

 a power (as gravity, heat, etc.), and the form of words in which we express 

 it, that is, its definition, should be consistent with the fundamental principles 



16 



