POPULAR SCIENTIFIC LECTURES. 



685 



thought that, however we may consider our- 

 selves to bo the centre and final object of 

 creation, we are but as dust on the earth ; 

 which again is but a speck of dust in the im- 

 mensity of space ; and the previous duration 

 of our race, even if we follow it far beyond 

 our written history, into the era of the lake 

 dwellings or of the mammoth, is but an in- 

 stant compared with the primeval times of 

 our planet, when living beings existed upon 

 it, whose strange and unearthly remains still 

 gaze at us from their ancient tombs ; and far 

 more does the duration of our race sink into 

 insignificance compared with the enormous 

 periods during which worlds have been in 

 process of formation, and will still contimie 

 to form when our sun is extinguished, and 

 our earth is either solidified hi cold or is 

 united with the ignited central body of our 

 system. 



But who knows whether the first living in- 

 habitants of the warm sea on the young 

 world, whom wo ought perhaps to honor as 

 our ancestors, would not have regarded our 

 present cooler condition with as much horror 

 as we look on a world without a sun ? Con- 

 sidering the wonderful adaptability to the 

 conditions of life which all organisms pos- 

 sess, who knows to what degree of perfection 

 our posterity will have been developed in 

 17,000,000 of years, and whether our fossilized 

 bones will not perhaps seem to them as 

 monstrous as those of the Ichthyosaurus 

 now do ; and whether they, adjusted for a 

 more sensitive state of equilibrium, will not 

 consider the extremes of temperature, within 

 which we now exist, to be just as violent and 

 destructive as those of the older geological 

 times appear to us ? Yea, even if sun and 

 earth should solidify and become motionless, 

 who could say what new worlds would not 

 be ready to develop life ? Meteoric stones 

 sometimes contain hydrocarbons ; the light 

 of the heads of comets exhibits a spectrum 

 which is most like that of the electrical light 

 in gases containing hydrogen and carbon. 

 But carbon is the element, which is charac- 

 teristic of organic compounds, from which 

 living bodies are built up. Who knows 

 whether these bodies, which everywhere 

 warm through space, do not scatter germs 

 of life wherever there is a new world, which 

 has become capable of giving a dwelling- 

 place to organic bodies'. And this life we 

 'mi'*'"t perhaps consider as allied to ours in 

 its primitive germ, however different might 

 be the form which it would assume in udapt- 

 ilig itself to its new dwelling-place. 



However this may be, that which most 

 arouses our moral feelings at the thought of 

 a future, though possibly very remote, cessa- 

 tion of all living creation on the earth, is 

 more particularly the question whether all 

 this life is not an aimless sport, which will 

 ultimately fall a prey to destruction by brute 

 force ? Under the light of Darwin's great 

 thonght we begin to see that not only pleas- 

 ure and joy, but also pain, struggle, and 

 death, are the powerful means by which na- 

 ture has built up her liner and more perfect 



forms of life. And we men know more par- 

 ticularly that in our intelligence, our civic 

 order, and our morality we are living on the 

 inheritance which our forefathers have 

 gained for us, and that which we acquire in 

 the same way will in like manner ennoble 

 the life of our posterity. Thus the individ- 

 ual, who works for the ideal objects of hu- 

 manity, even if in a modest position, and in 

 a limited sphere of activity, may bear with- 

 out fear the thought that the thread of his 

 own consciousness will one day break. But 

 even men of such free and large order of 

 minds ns Lessing and David Strauss could 

 not reconcile themselves to the thought of a 

 final destruction of the living race, and with 

 it of all the fruits of all past generations. 



As j r et we know of no fact, which can bo 

 established by scientific observation, which 

 would show that the finer and complex forms 

 of vital motion could exist otherwise than ia 

 the dense material of organic life ; that it can 

 propagate itself as the sound-movement of a 

 string can leave its originally narrow and 

 fixed home and diffuse itself in the air, keep- 

 ing all the time its pitch, and the most deli- 

 cate shade of its color-tint ; and that, when 

 it meets another string attuned to it, starts 

 this again or excites a flame ready to sing to 

 the same tone. The flame even, which, of 

 all processes in inanimate nature, is the 

 closest typo of life, may become extinct, but 

 the heat which it produces continues to exist 

 indestructible, imperishable, as an invisible 

 motion, now agitating the molecules of pon- 

 derable matter, and then radiating into 

 boundless space as the vibration of an ether. 

 Even there it retains the characteristic pecu- 

 liarities of its origin, and it reveals its his- 

 tory to the inquirer who questions it by the 

 spectroscope. United afresh, these rays may 

 ignite a new flame, and thus, as it were, ac- 

 quire a new bodily existence. 



Just as the flame remains the same in ap- 

 pearance, and continues to exist with the 

 same form and structure, although it draws 

 every minute fresh combustible vapor, and 

 fresh oxygen from the air, into the vortex of 

 its ascending current ; and just as the wave 

 goes on in unaltered form, and is yet being 

 reconstructed every moment from freah par- 

 ticles of water, so also in the living being, it 

 ia. not the definite niiiss of substance, which 

 now constitutes the body, to which the con^ 

 tinuance of the individual is attached. For 

 the material of the body, like that of the 

 flame, is subject to continuous and compara- 

 tively rapid change a change the more 

 rapid, the livelier the activity of the organ* 

 in question. Home constituents are renewed 

 from day to day, some from month to month, 

 and others only after years. That which con- 

 tinues to exist us a particular individual is 

 like the flume and the wave only the form 

 of motion which continually attracts fresh 

 matter into its vortex and expels the old. 

 The observer with a deaf ear only recognizes 

 the vibration of sound as long as it is visible 

 and can be f-lt, bound up with heavy matter. 

 Axe our sensvn, in reference to life, liko the 



