ANALOGY. 299 



long ago as 1591, that the stars may be suns attended 

 perhaps by planets like our earth. This is the most 

 probable first assumption, supported in some degree by 

 very recent spectrum observations, which show the simi- 

 larity of light derived from many stars with that of the 

 sun. But at the same time we learn by the prism that 

 there are nebulae and stars in conditions widely different 

 from anything known in our system. In the course of 

 time the analogy may perhaps be restored to comparative 

 completeness by the discovery of many suns in various 

 stages of nebulous condensation. The history of the evo- 

 lution of our own world may, as it were, be traced back 

 in bodies less developed, or traced forwards in systems 

 more advanced towards the dissipation of energy, and the 

 extinction of life. As in a great workshop, we may per- 

 haps see the material work of Creation as it has variously 

 progressed through thousands of millions of years. 



By the careful delineation and classification of the 

 nebulas and stellar systems, we may hope in time to find 

 some parallel even to that apparently space-filling system 

 of the Milky Way. Michell pointed out that the Pleiades 

 form a remarkable group of worlds, and he thought that 

 it might present an analogy to the sun and its immediate 

 neighbours. The observations of the Herschels and other 

 more recent astronomers, show that we really belong to 

 a vast stratum of worlds of a peculiar split form, in- 

 cluding countless myriads of stars of various sizes. The 

 belief in analogy is irresistible, and astronomers have 

 already looked into the depths of space, hoping to find 

 distant nebulous specks which might resemble the sup- 

 posed form of the Milky Way, and extend our know- 

 ledge to a higher order of universes. Such expectations 

 are probably premature, or even unfounded ; neverthe- 

 less in the forms of the nebulae we may find much in- 

 struction. The spiral form disclosed in many bodies 



