44 MATTER AND FORCE, IN PHYSICAL PHENOMENA. 



which renders it the great motor in the universe. It 

 combines with, or is modified by, other motor forces, 

 as in the rotation of the earth, but we cannot corre- 

 late it with any of those which exhibit polarities or 

 dualities of action, and are mutually convertible under 

 equivalents of change. Gravitation still stands alone 

 in the simple sublimity of its one great law. If we 

 ever get nearer to a true theory of the power, it will 

 probably be through some new knowledge of the 

 atomic conditions of matter. To these infinitesimal 

 parts, and their attractions and repulsions, we may best 

 look for the source of a power universal and perma- 

 nent ; and however vague the conception, there is none 

 other to which we can attach belief. The theory 

 of Mosolti (anticipated by (Epinus) taking this founda- 

 tion, sought in mathematical forms to derive gravity as 

 a residual power from a balance of attractions and re- 

 pulsions, with the postulate of an electric atmosphere 

 to each atom. This hypothesis, like that of Lesage, 

 has lain dormant ever since. It wants the evidence of 

 facts, though justified, I think, in thus seeking through 

 individual atoms the origin of a power so manifestly 

 derived from the concentration of individual forces. 



But even could proof be pushed thus far, there still 

 remains the crucial question, What is the power pro- 

 ducing these atomic conditions or actions, which, con- 

 centrated more or less, we call gravitation ? It is in 

 effect the same question already applied to other 

 modes of force. Are they actual powers extraneous 

 to matter though acting upon it ? Or may we gene- 

 ralise yet farther, in supposing a single force in the 



