414 . FRAGMENTS OF SCIENCE. 



ceivable. The tendency, indeed, of modern science is to 

 break down the wall of partition between organic and inor- 

 ganic, and to reduce both to the operation of forces which 

 are the same in kind, but whose combinations differ in com- 

 plexity. 



Consider now the question of personal identity, in rela- 

 tion to this of molecular form. Twenty-six years ago, 

 Mayer, of Heilbronn, with that power of genius which 

 breathes large meanings into scanty facts, pointed out that 

 the blood was " the oil of life," the combustion of which, 

 like that of coal in grosser cases, sustained muscular action. 

 The muscles are the machinery by which the dynamic power 

 of the blood is brought into play. Thus the blood is con- 

 sumed. But the whole body, though more slowly than the 

 blood, wastes also, so that after a certain number of years 

 it is entirely renewed. How is the sense of personal iden- 

 tity maintained across this flight of molecules ? To man as 

 we know him, matter is necessary to consciousness, but the 

 matter of any period may be all changed, while conscious- 

 ness exhibits no solution of continuity. Like changing 

 sentinels, the oxygen, hydrogen, and carbon that depart 

 seem to whisper their secret to their comrades that arrive, 

 and thus, while the Non-ego shifts the Ego remains intact. 

 Constancy of form in the grouping of the molecules, and 

 not constancy of the molecules themselves, is the correlative 

 of this constancy of perception. Life is a wave which in 

 no two consecutive moments of its existence is composed 

 of the same particles. 



Supposing, then, the melocules of the human body 

 instead of replacing others, and thus renewing a preexist- 

 ing form, to be gathered first hand from Nature and put 

 together in the same relative positions as those which they 

 occupy in the body ; that they have the self-same forces and 

 distribution of forces, the self-same motions and distribution 

 of motions would this organized concourse of molecules 



