476 POPULAR SCIENCE MONTHLY. 



which exists between heat and motion." He includes both animal and 

 vegetable vitality in his generalization. 



"The life of man, or of any of the higher animals, essentially con- 

 sists in the manifestation of forces of various kinds, of which the or- 

 ganism is the instrument." 



All organic life involves the direction of nature's forces and their 

 utilization by direction of the energies; but this striking and important 

 distinction is observed, as Carpenter first definitely asserted: The animal 

 employs energy derived by the disintegration of vegetable growth to its 

 will-directed, and to its internal automatic, work; while the vegetable di- 

 rects the energy of the sun's rays and of chemical action to the building 

 up of new organic matter into its life-forms. A cycle thus transfers and 

 transforms energy radiated to the earth from the sun, building up the 

 vegetable, sacrificing the structure in the building of the animal or- 

 ganism, breaking down the animal structure again, and setting free the 

 circling energy to continue its progress along other paths into other or- 

 ganic matter, or elsewhere, as directing agencies may compel. 



Thus, in all nature and in all manifestations of natural law and of 

 motion, general experience has satisfied us that matter is persistent, that 

 it is endowed with inalienable properties which include the so-called 

 physical forces, similarly persistent in their character and methods of 

 action and their intensities, and that energy, a property of matter in 

 motion, is also persistent, but not also permanently affecting any given 

 mass; its total quantity is invariable, but it may be distributed indefi- 

 nitely, transferred in any manner and transformed to any extent, irre- 

 spective of other than quantitative measures of matter affected. Matter 

 not only permanently retains its characteristic forces, but, reciprocally, 

 the forces permanently require and maintain matter as their residence. 

 No exception to this constancy of union of matter and forces is yet 

 known, and the only question now remaining to be fully answered is: 

 How far may such relations be traced into the more intangible realms of 

 nature and life and consciousness. 



Herbert Spencer has stated the fundamental idea of science in this 

 field most concisely, accurately and clearly. He says in 'First Prin- 

 ciples': "We cannot go on merging derivative truths in these wider 

 truths from which they are derived without reaching at last a wider 

 truth which can be merged in no other or derived from no other. And 

 whoever contemplates the relation in which it stands to the truths of 

 science in general will see that this truth, transcending demonstration, is 

 the Persistence of Force." Indeed, Faraday had already, years before, 

 asserted this law to be the highest that our faculties can appreciate in 

 physical science. In fact, as we may perhaps still more strongly put it: 

 The Law of the Persistence of Substance, including its every attribute, 



