MATTER AND ENERGY. 43 



and certain stellar bodies which are not what they 

 were, furnish a foundation for such lucubrations. 

 But, granting that a celestial body a satellite, for in- 

 stance does grow old and exhibit decrepitude, that is 

 not conclusive that its substance in other forms, may 

 not again take part in cosmical affairs. A mass of 

 matter may be resolved into its elements into nebu- 

 lous atoms and have its particles aggregated again 

 into a sidereal sphere, the processes of diffusion and 

 concentration repeating themselves indefinitely and 

 eternally. 



THE NEBULAR THEORY. 



Before proceeding at greater length I would call 

 attention to a somewhat antiquated hypothesis, which 

 is that in the beginning (?) matter was not in aggre- 

 gated masses in solar systems but in an exceed- 

 ingly tenuous form in gasses and nebulous states ; 

 and that heat, a form of energy diffusive in character, 

 kept the particles apart, until cooling and condensing 

 processes broke in upon the status of things, and the 

 gravitative force drew the particles together or into 

 intimate relationship. The opposing or antagonistic 

 energies gravitation and repulsion through a sub- 

 sidence of heat, the repelling force, resulted in a sub- 

 division of the nebulous stuff, and an aggregation of 

 it into a multitude of sidereal bodies into solar sys- 

 tems as we now understand them. The forces cited 

 were sure to keep the more or less eccentric masses in 

 revolving motions, some bodies moving rapidly, and 

 others with restricted velocities, and with a liability 

 to collide or come in contact. 



Such is the merest outline of the workings of the 

 nebular theory; and while it has had some serious ob- 

 jections raised against it, they are not insurmountable. 



