286 THE POPULAR SCIENCE MONTHLY. 



the assumption of a resisting medium. On tlie other hand, it seems 

 exceedingly natural to suppose that some matter in a very thin state 

 is diffused about the planetary spaces. Then we have another consid- 

 eration : just as the sun and moon make tides x;pou the sea, so the 

 planets make tides upon the sun. If we consider the tide which the 

 earth makes upon the sun, instead of being a great wave lifting the 

 mass of the sun up directly under the earth, it lags behind, the result 

 is that the earth, instead of being attracted to the sun's centre, is at- 

 tracted to a point behind the centre. That retards the earth's motion, 

 and the effect of this upon the planet is to make its orbit larger. That 

 planet disturbing all the other planets, the consequence is, that we 

 have the earth gradually going away from the sun, instead of falling 

 into it. 



In any case, all we know is that the sun is going out. If we fall 

 into the sun then we shall be fried ; if we go away from the sun, or 

 the sun goes out, then we shall be frozen. So that, so far as the earth 

 is concerned, we have no means of determining what will be the 

 character of the end, but we know that one of these two things must 

 take place in time. But in regard to the whole universe, if we were 

 to travel forward as we have traveled backward in time, consider 

 things as falling together, we should come finally to a great central 

 mass, all in one piece, which would send out waves of heat through a 

 perfectly empty ether, and gradually cool itself down. As this mass 

 got cool it would be deprived of all life or motion ; it would be just a 

 mere enormous frozen block in the middle of the ether. But that con- 

 clusion, which is like the one that we discussed about the beginning 

 of the world, is one which we have no right whatever to rest upon. 

 It depends upon the same assumption that the laws of geometry and 

 mechanics are exactly and absolutely true, and that they have con- 

 tinued exactly and absolutely true for ever and ever. Such an assump- 

 tion we have no right whatever to make. We may therefore, I think, 

 conclude about the end of things that, so far as the earth is concerned, 

 an end of life upon it is as probable as science can make any thing, 

 but that in regard to the universe we have no right to draw any con- 

 clusion at all. So far we have considered simply the material exist- 

 ence of the earth ; but of course our greatest interest lies not so much 

 with the material things upon it, its organized things, as with another 

 fact which goes along with that, and which is an entirely different 

 one the fact of the consciousness that exists upon the earth. We 

 find very good reason indeed to believe that this consciousness in the 

 case of any organism is itself a very complex thing, and that it cor- 

 responds part for part to the action of the nervous system, and more 

 particularly of the brain of that organized thing. There are some 

 whom such evidence has led to the conclusion that the desti'uction 

 which we have seen reason to think probable of all organized beings 

 upon the earth will lead also to the final destruction of the conscious- 



