COSMIC EXCHANGE OF MATTER AND LIFE 441 



cannot yet predict earthly weather five hundred years hence,! 

 as he will be able not distantly to do. Probably the solution of 

 the one problem will be reached almost as soon as the other. 



But if the interesting speculation here detailed could be 

 justified, we should then be in possession of a conceivable 

 mechanism by which life is propagated and distributed through- 

 out the universe. The implication of this will hardly escape. 

 The cosmic exchange of matter means that the material of the 

 universe is more or less alike. Not for the most distant planet 

 of the most distant star can we conceive of any other forces 

 in play than those which exist upon our earth and within our 

 solar system. It follows that with the same forces, acting upon 

 the same materials, the physical evolution of the suns and 

 planets will be the same throughout. These are the conclusions 

 to which every scrap of knowledge we possess unmistakably 

 points. 



If the course of stellar and planetary evolution is the same, 

 it follows that vital evolution and the forms of life will differ 

 little. This we should infer from whatever point of view we 

 consider its origin. If it be an incident of planetary cooling 

 that is to say, spontaneous to each cooling planet or if it be 

 propagated from one world system to another, after the manner 

 so daringly imagined by Arrhenius, the result would be the 

 same. 



We may go further. Intelligence that is, our mental 

 faculty is simply a function of a definite physical organisa- 

 tion. Then just as it is impossible to conceive life qualitively 

 different from that upon the earth, so nowhere in the universe 

 can we conceive of forms of intelligence of a different order 

 than our own. The development may be higher as we know 

 that it may be lower. It may envisage more facts, its deduc- 

 tions may be swifter, its generalisations wider. Its limitations 

 will remain more or less our limitations. The problems that are 

 transcendent to us are, we may infer, transcendent throughout 

 the universe, so far as that universe will ever be known to us. 



Such at least seems the implication of that unending process 

 of give and take which we now know to be at work through- 

 out the last corners of the stellar scheme. If we could travel 

 for a lifetime with a thousand times the swift rush of light, we 

 should probably fail to discover any world, any race, any in- 

 telligence differing perhaps more widely from our own than 



