to shew this to be a reasonable postulatum, when understood in a general sense; for it is all one to the purpose of the foregoing theory, whether the motions in the medullary substance be the physical cause of the sensations, according to the system of the schools; or the occasional cause, according to Malbranche; or only an adjunct, according to Leibnitz. However, this is not supposing matter to be endued with sensation, or any way explaining what the soul is; but only taking its existence and connexion with the bodily organs in the most simple case, for granted, in order to make farther inquiries. Agreeably to which I immediately proceed to determine the species of the motion, and by determining it, to cast light on some important and obscure points relating to the connexion between the body and the soul in complex cases.
It does indeed follow from this theory, that matter, if it could be endued with the most simple kinds of sensation, might also arrive at all that intelligence of which the human mind is possessed: whence this theory must be allowed to overturn all the arguments which are usually brought for the immateriality of the soul from the subtlety of the internal senses, and of the rational faculty. But I no ways presume to determine whether matter can be endued with sensation or no. This is a point foreign to the purpose of my inquiries. It is sufficient for me, that there is a certain connexion, of one kind or other, between the sensations of the soul, and the motions excited in the medullary substance of the brain; which is what all physicians and philosophers allow.
I would not therefore be any way interpreted so as to oppose the immateriality of the soul. On the contrary, I see clearly, and acknowledge readily, that matter and motion, however subtilely divided, or reasoned upon, yield nothing more than matter and motion still. But then neither would I affirm, that this consideration affords a proof of the soul’s immateriality. In like manner the unity of consciousness seems to me an inconclusive argument. For consciousness is a mental perception; and if perception be a monad, then every inseparable adjunct of it must be so too, i.e. vibrations, according to this theory, which is evidently false. Not to mention, that it is difficult to know what is meant by the unity of consciousness.
But it is most worthy of notice, that the immateriality of the soul has little or no connexion with its immortality; and that we ought to depend upon Him who first breathed into man the breath of the present life, for our resurrection to a better. All live unto him. And if we depend upon any thing else besides him, for any blessing, we may be said so far to renounce our allegiance to him, and to idolize that upon which we depend.
