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Rh physiological theories relative to the connection between soul and body. Of these theories, however, groundless and puerile as they are, it is necessary for me, before I proceed farther, to say a few words, on account of their extensive and lasting influence on the subsequent history of the science of Mind, not only upon the Continent, but in our own Island.

The hypothesis of Descartes, which assigns to the soul for its principal seat the pineal gland or conarion, is known to every one who has perused the Alma of Prior. It is not, perhaps, equally known, that the circumstance which determined him to fix on this particular spot, was the very plausible consideration, that, among the different parts of the brain, this was the only one he could find, which, being single and central, was fitted for the habitation of a being, of which he conceived unity and indivisibility to be essential and obvious attributes. In what manner the animal spirits, by their motions forwards and backwards in the nervous tubes, keep up the communication between this gland and the different parts of the body, so as to produce the phenomena of perception, memory, imagination, and muscular motion, he has attempted particularly to explain; describing the processes by which these various effects are accomplished, with as decisive a tone of authority, as if he had been demonstrating experimentally the circulation of the blood. How curious to meet with such speculations in the works of the same philosopher, who had so clearly perceived the necessity, in studying the laws of Mind, of abstracting entirely from the analogies of Matter; and who, at the outset of his inquiries, had carried his scepticism so far, as to require a proof even of the existence of his own body! To those, however, who reflect with attention on the method adopted by Descartes, this inconsistency will not appear so inexplicable as at first sight may be imagined; inasmuch as the same scepticism which led him to suspend his faith in his intellectual faculties till he had once proved to his satisfaction, from the necessary veracity of God, that these faculties were to be regarded as the divine oracles, prepared him, in all the subsequent steps of his progress, to listen to the suggestions of his own fallible judgment, with more than common credulity and confidence.

The ideas of Descartes, respecting the communication between soul and body, are now so universally rejected, that I should not have alluded to them here, had it not been for their manifest influence in producing, at the distance of a century, the rival hypothesis of Dr Hartley. The first traces of this hypothesis occur in some queries of Sir Isaac Newton, which he was probably induced to propose, less from the conviction of his own mind, than from a wish to turn the attention of philosophers to an examination of the correspondent part of the Cartesian system. Not that I would be understood to deny

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