THE GENERAL CONDITIONS OF LIFE 345 



not the cessation of the existence of the individual, but the transform- 

 ation of living substance into a corpse, i.e., into lifeless substance, is 

 the criterion for the conception of death, then the question of the 

 existence of immortal organisms coincides with that of the 

 immortality of living substance in general. But the conception of 

 living substance as immortal will be accepted by scarcely any one 

 who bears in mind the characteristic peculiarity of living substance, 

 viz., that it continually decomposes, or, in other words, dies. There 

 is no living substance that, so long as it is living at all, is not 

 continually decomposing in some parts, while being regenerated in 

 others. No living molecule is spared this decomposition ; the latter, 

 however, does not seize upon all molecules at the same time ; while 

 one is decomposing, another is being constructed, and so on. One 

 living particle affords the conditions for the origin of another or 

 several others, but itself dies. The particles newly formed in 

 turn give origin to others and, likewise, die. In this manner living 

 substance is continually dying, without life itself ever becoming ex- 

 tinct. Hence, there is no immortality of living substance itself, but 

 merely a continuity in its descent. Life as a complex motion has 

 never become extinct from the time of its first appearance upon the 

 earth down to the present, but living substance in the form of bodies 

 is dying continually. Life as a complex motion does not possess 

 true immortality any more than it has existed from eternity. Just 

 as the earth in its development has passed through a time when no 

 life could yet exist, so it will again pass through a time when all life 

 must become extinct. The moon now shows us the fate that hangs 

 over the earth. From the liquid drop which once was cast off from 

 the great, glowing mass of the earth, it has in a briefer time passed 

 through essentially the same development as the earth which gave 

 it its origin. The intense cold that now prevails upon it will 

 sometime take possession of the earth, and annihilate all life upon 

 the latter. So far as the physical world is concerned, immortality 

 and eternity are the properties not of any special material system, 

 such as living substance, or of any special complex motion, such as 

 life, but only of elementary matter and its motion. 



Heraclitus compared life with fire. As has been shown above, 

 such a comparison is a pertinent one. Our consideration of vital 

 conditions makes this more evident. It has been shown that life 

 like fire is a phenomenon of nature which appears as soon as the 

 complex of its conditions is fulfilled. If these conditions are all 

 realised, life must appear with the same necessity as fire appears 

 when its conditions are realised ; likewise, life must cease as soon 

 as the complex of its conditions has undergone disturbance, and 

 with the same necessity with which fire is extinguished, when the 

 conditions for its maintenance cease. 



If, therefore, all vital conditions had been investigated in their 



