In the last chapter I have indicated reasons for believing that the sidereal system extends far beyond the range of the most powerful telescopes man has yet been able to construct. It need hardly be said that, supposing this view to be correct, we cannot possibly see any external galaxies, unless they surpass our own many thousands of times in richness and splendour. Every analogy that we have for our guidance points to the conclusion that, if our galaxy have limits, and there exist in space other galaxies, then those outer systems must be separated from ours by spaces exceeding the dimensions of the several galaxies many thousand or many million fold in extent. We know that the distances separating the satellites from their primaries exceed in an enormous ratio the dimensions of the satellites. The distances separating the planets from each other exceed in an enormous ratio the dimensions of the planets. The distances separating our solar system from others enormously exceed the dimensions of the various solar systems. And we may conclude that in all probability the distances separating our sidereal system from other similar systems in space, must exceed in an enormous ratio the dimensions of our galaxy, and of all other such systems.