It were a mistake to think that what is here said derogates in the least from the reality of things.  The unthinking beings perceived by sense exist in those unextended, indivisible substances, or spirits, which act, think, and perceive them; whereas philosophers vulgarly hold that the sensible qualities exist in an inert, extended, unperceiving substance, which they call “matter,” to which they attribute a natural subsistence distinct from being perceived by any mind whatsoever, even the eternal mind of the Creator.

As we have shown the doctrine of matter to have been the main support of scepticism, so likewise upon the same foundation have been raised all the impious schemes of atheism and irreligion.  All these monstrous systems have so visible and necessary a dependence on this supposed material substance that, when this cornerstone is once removed, the whole fabric cannot choose but fall to the ground.

On the same principle does not only fatalism but also idolatry depend in all its varying forms.  Did men but consider that the sun, moon, and stars, and every other object of the senses, are only so many sensations in their minds, which have no other existence but barely being perceived, they would never fall down and worship their own ideas, but rather address their homage to that Eternal Invisible Mind which produces and sustains all things.

As in reading books, a wise man will choose to fix his thoughts on the sense rather than lay them out on grammatical remarks; so, in perusing the volume of Nature, it seems beneath the dignity of the mind to affect an exactness in reducing each particular phenomenon to general rules, or showing how it follows from them.  We should propose to ourselves nobler views, such as to recreate and exalt the mind, with a prospect of the beauty, order, extent, and variety, of natural things; hence, by proper inferences, to enlarge our notions of the grandeur, wisdom, and beneficence of the Creator.

The reason that is assigned for our being thought ignorant of the nature of spirits is our not having an idea of them.  But it is manifestly impossible that there should be any such idea.  A spirit is the only substance or support wherein the unthinking beings or ideas can exist; but that this substance which supports or perceives ideas should itself be an idea is absurd.

From the opinion that spirits are to be known after the manner of an idea or sensation have arisen many heterodox tenets and much scepticism about the nature of the soul.  It is even probable that this opinion may have produced a doubt in some whether they had any soul at all distinct from their body, since they could not find that they had an idea of it.  But the spirit is a real thing, which is neither an idea nor like an idea.  What I am myself, that which I denote by the term “I,” is what we mean by soul or spiritual substance; and we know other spirits by means of our own soul, which in that sense is an image or idea of them.