Read it through once

But, it will be objected, the inhabitants of the various planets of this and other solar systems; and the existence of a Power bearing the same relation to all that we perceive and are, as what we call a cause does to what we call effect, were never subjects of sensation, and yet the laws of mind almost universally suggest, according to the various disposition of each, a conjecture, a persuasion, or a conviction of their existence. The reply is simple; these thoughts are also to be included in the catalogue of existence; they are modes in which thoughts are combined; the objection only adds force to the conclusion, that beyond the limits of perception and thought nothing can exist.