firmaments, consisting, like the Galaxy, of innumerable stars. They may appear as single, hazy stars, but they are the combined light of countless hosts. These groups are separated by gulfs which it would require millions of years for a ray of light to traverse.
As we in thought travel from firmament to firmament, we see new forms constantly presented to our view. Each firmament has some bond of unity, and, generally, a symmetrical structure. However much they differ, a tendency to the spiral structure may be discovered. One cannot look at the figures of the spiral nebulæ without having suggested the idea of vast vortices, in which streams of stars are hastening on to some grand consummation. There is nothing fixed or final in the heavens; all things are passing through cycles of decay or revivification. As there are silent molecular changes going on in the most solid masses on the earth's surface, so these suns, which to a mind of superior grasp may appear as only single particles of which the nebula is the mass, are in constant motion in the galaxy to which they belong.
But where are we to stop? Are we to assume that the firmament or resolvable nebula is the last step? or, are we to look for some higher unity, under which these groups may be subsumed? Speculations connected with the indestructibility of force, have led to the idea that all the worlds and system which astronomy has revealed, are included within one vast
