DIRECT EQUILIBRATION. 433 



which has its involved perturbations, that now increase and 

 now decrease, is heie presented to us. Suppose a iiew 

 force were brought to bear on this moving equilibrium say 

 by the arrival of some wandering mass, or by an additional 

 momentum given to one of the existing masses what would 

 be the result ? If the strange body or the extra force were 

 very large, it might so derange the entire system as to cause 

 its collapse : by overthrow of its rhythmical movements, the 

 moving equilibrium might rapidly be changed into a com- 

 plete equilibrium. But what if the incident force, falling on 

 the system from without, proved insufficient to overthrow it? 

 There would then arise a set of perturbations which would, 

 in the course of an enormous period, slowly work round into 

 a modified moving equilibrium. The effects primarily im- 

 pressed on the adjacent masses, and in a smaller degree on 

 the remoter masses, would soon become complicated with the 

 secondary effects impressed by the disturbed masses on one 

 another ; and these again with tertiary effects. "Waves of 

 perturbation would continue to be propagated throughout 

 the entire system ; until, around a new centre of gravity, 

 there had been established a set of planetary motions more 

 or less different from the preceding ones. All this would 

 necessarily follow from the truth, that any new force brought 

 to bear on a moving equilibrium, must gradually be used up 

 in overcoming the forces that resist the divergence it gener- 

 ates : which antagonizing forces, being then no longer op- 

 posed, set up a counter-action, ending in a compensating 

 divergence in the opposite direction, that is followed by a 

 re-compensating divergence ; and so on, until there is either 

 established some additional rhythmical movement, or some 

 equivalent modification of the pre-existing rhythmical move- 

 ments. Now though instead of being, like the Solar 

 System, in a state of independent moving equilibrium, an 

 organism is in a state of dependent moving equilibrium 

 (First Principles, 130) ; yet this does not prevent the 

 manifestation of the same law. Every animal daily obtains 



