28 WONDER AND MYSTERY. 



dreds of years for their light, moving at that inconceivably 

 great velocity, to reach the earth ! Think of the enormous 

 magnitude of a sphere traversed by the radiance of such a 

 star ! Now every one of the millions of stars and if we 

 include, as we ought to do, with those that can be seen by 

 the naked eye, those which are brought to view by the tel 

 escope, either as single stars or are resolved from nebulae, 

 the number is to be reckoned at thousands of millions is 

 surrounded by a sphere of radiance which must extend to 

 us, and all these spheres occupy the same space, entering 

 into, crossing, and interpenetrating each other in every di- 

 rection, so that, when you hold up a needle in the evening 

 air on a clear night, there are millions upon millions of dis- 

 tinct radiations passing through the eye of it in both direc- 

 tions, encountering each other at every possible angle and 

 with every conceivable disparity of force. And yet each 

 one of these radiations maintains its way so entirely unin- 

 terrupted and undisturbed by the rest, that you can select 

 any one of them you choose, and, by conducting a suffi- 

 cient portion of it from the space around, by means of the 

 telescope, to your eye, you can there produce a picture of 

 its source upon the retina as clear, and distinct, and as 

 sharply defined as if its own radiance was the only one 

 emitted, and had the entire and exclusive occupation of 

 the field. 



There is no way of escaping from or diminishing the un- 

 utterable wonderfulness of these facts. I have only called 

 the emission a radiance that is, something radiated 

 without intending to say in what it consists. It has been 

 thought to consist of streams of infinitely minute particles 

 of matter. It is now generally considered as an undula- 

 tion or vibration in some extremely subtle medium dif- 

 fused through space, to which the name luminiferous ether 

 has been given, which phrase means, simply, the unknown 



