202 THE POPULAR SCIENCE MONTHLY. 



cause it enabled men to rise above the selfishness and the sensuality 

 which otherwise threatened to choke the higher impulses of our nature. 

 But it was the existence of those impulses which gave it its strength, 

 and not any of the metaphysical arguments which can only appeal to 

 a very few exceptional minds. Religions thrive by a kind of natural 

 selection ; those which do not provide expression for our best feelings 

 crush out their rivals, not those which are inferred by a process of ab- 

 stract reasoning. To be permanent, they must bear the test of reason ; 

 but they do not owe to it their capacity for attracting the hearts of 

 men. The inference, therefore, from the universality of any creed is 

 not that it is true, for that would prove Buddhism or Mohammedan- 

 ism as well as Christianity ; but that it satisfies more or less complete- 

 ly the spiritual needs of its believers. And, therefore, we may be cer- 

 tain that, if the various tendencies which we have summed up in the 

 name of Darwinism should ultimately become triumphant, they must 

 find some means, though it is given to nobody as yet to define them, 

 of reconciling those instincts of which the belief in immortality was a 

 product. The form may change we cannot say how widely but the 

 essence, as every progress in the scientific study of religions goes to 

 show, must be indestructible. When a new doctrine cuts away some 

 of our old dogmas, we fancy that it must destroy the vital beliefs to 

 which they served as scaffolding. Doubtless it has that effect for a 

 time in those minds with whom the association has become indissolu- 

 ble. That is the penalty we pay for progress. But we may be sure 

 that it will not take root till in some shape or other it has provided the 

 necessary envelopes for the deepest instincts of our nature. If Dar- 

 winism demonstrates that men have been evolved out of brutes, the 

 religion which takes it into account will also have to help men to bear 

 in mind that they are now different from brutes. Fraser^s Magazine. 







ACTION OF DARK RADIATIONS. 



By PEOF. TYNDALL. 



VTTE now enter upon another inquiry. "We have to learn definitely 

 V V what is the meaning of solar light and solar heat ; in what way 

 they make themselves known to our senses ; by what means they get 

 from the sun to the earth, and how, when there, they produce the 

 clouds of our atmosphere, and thus originate our rivers and our gla- 

 ciers. 



If in a dark room you close your eyes and press the eyelid with 

 your finger-nail, a circle of light will be seen opposite to the point 

 pressed, while a sharp blow upon, the eye produces the impression of a 



