THE RE-ACTIONS OP ORGANIC MATTER ON FORCES. 57 



arrangements, minute sensible motions so caused, may be ac- 

 cumulated into large sensible motions. There is, liowever, 

 no evidence to support this supposition. 



§ 23. But the truths wliich it is here our business espe- 

 cially to note, are quite independent of hypotheses or inter- 

 pretations. It is sufficient for the ends we have in view, to 

 observe that organic matter does exhibit these several conspi- 

 cuous re-actions, when acted on by incident forces : it is not 

 requisite that we should know how these re-actions originate. 



In the last chapter were set forth the several modes in 

 which incident forces cause re-distributions of organic mat- 

 ter ; and in this chapter have been set forth the several modes 

 in which is manifested the motion accompanying this re-dis- 

 tribution. There we contemplated under its several aspects, 

 the general fact, that in consequence of its extreme instability, 

 organic matter undergoes extensive molecular re-arrange- 

 ments, on very slight changes of conditions. And here we 

 have contemplated under its several asjaects, the correlative 

 general fact, that during these extensive molecular re-arrange- 

 ments, there are necessarily evolved large amounts of force. 

 In the one case the atoms of which organic matter consists, 

 are regarded as changing from positions of unstable equi- 

 librium to positions of stable equilibrium ; and in the other 

 case they are regarded as giving out in their falls from 

 unstable to stable equilibrium, certain momenta — momenta 

 that may be manifested as heat, light, electricity, nerve- 

 force or mechanical motion, according as the conditions 

 determine. 



I will add *)nly that these -evolutions of force are rigoi-- 

 ously dependent on these changes of matter. It is a corol- 

 lary from that primordial truth which, as we have seeji, 

 underlies all other truths, {First Prlnc'qAes, §§ 76, 141,) 

 that whatever amount of power tin organism expends in 

 any shape, is the correlate and equivalent of a power that 

 was taken into it from without. On the one hand, it 



