ETHER. 775 



No theory of the constitution of the aether has yet been invented which 

 will account for such a system of molecular vortices being maintained for an 

 indefinite time without their energy being gradually dissipated into that irregular- 

 agitation of the medium which, in ordinary media, is called heat. 



Whatever difficulties we may have in forming a consistent idea of the con- 

 stitution of the aether, there can be no doubt that the interplanetary and 

 interstellar spaces are not empty, but are occupied by a material substance or 

 body, which is certainly the largest, and probably the most uniform body of 

 which we have any knowledge. 



Whether this vast homogeneous expanse of isotropic matter is fitted not 

 only to be a medium of physical interaction between distant bodies, and to 

 fulfil other physical functions of which, perhaps, we have as yet no conception, 

 but also, as the authors of the Unseen Universe seem to suggest, to con- 

 stitute the material organism of beings exercising functions of life and mind 

 as high or higher than ours are at present, is a qiiestion far transcending the 

 limits of physical speculation. 



