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impulses and volition; but from such motions it seems impossible to account for sensation or volition. We can conceive no variety in these motions, but what relates to degree, duration, and succession, and it seems impossible to believe that sensation can be the result of such motions, or that ideas can arise from any succession or train of them. Certain persons will therefore I doubt not continue to think that sensation, remembrance, comparison, judgment, and volition, are properties of some distinct substance.
The essences or primitive parts of what we call matter, are too subtile to be perceived by our senses, and seem even to elude our conceptions. Is it not then most philosophical to acknowledge our ignorance on these points, and to speak of what we do know, the properties of the different species of substances in na
ture. Thus we seem to be acquainted with the properties of the aggregate forms of that substance which is cognizable to the eye and touch, and which we then call matter; we seem to be as sured of the existence, and to know something of the properties, of a subtile substance which pervades all nature; and if we are allowed to know any thing, we surely may be admitted to know the properties of our own minds.
How diversified are our perceptions, how admirably are they adapted to our wants and gratifications! for all beauty of prospect, all melody of sound, all variety of odour, must by the eye of reason be perceived to result from the masses or molecules of surrounding matter, being in various states of motion or of rest; of which circumstances we have notice by the actions they induce in our ner.
vous fibrils. Such variety of perceptions I can only consider as the effect of the peculiar properties of that which feels, remembers, reasons, and wills, and which seems connected with the brain alone.
The conclusion to be drawn from this examination of the functions of the nervous system is curious and interesting. We perceive an exact correspondence between those opinions which result from physiological researches, and those which so naturally arise from the suggestions of reason that some have considered them as intuitive. For most reflecting persons in all ages have believed, and indeed it seems natural to believe, what modern physiology also appears to teach, that in the human body there exists an as'semblage of organs, formed of common inert matter, such as we see after death, a principle of life and action, and a set
tient and rational faculty, all intimately connected, yet each apparently distinct from the other. So intimate, indeed, is the connection as to impose on us the opinion of their identity. The body springs and bounds as though its inert fabric were alive; yet have we good reasons for believing that life is distinct from organization. The mind and the actions of life affect each other. Failure or disturbance of the actions of life prevent or disturb our feelings, and enfeeble, perplex, or distract our intellectual operations. The mind equally affects the actions of life, and thus influences the whole body. Terror seems to palsy all its parts, whilst contrary emotions cause the limbs to struggle, and become contracted from energy. Now though these facts may countenance the idea of the identity of mind and
life, yet have we good reasons for believing that they are perfectly distinct. Whilst, therefore, on the one hand, I feel interested in oppugning those physiological opinions which tend to confound life with organization ; I would, on the other, equally oppose those which confound perception and intelligence with mere vitality.
In the first lecture I endeavoured to shew that Mr. Hunter's Theory of Life was verifiable, and that it afforded the most rational solution of the cause of irritability, which had hitherto been of. fered to the public. It now appears that it does not essentially differ from that of the best physiologists, with regard to the explanation it affords of the nervous functions. As it is impossible to review all the phaenomena of these functions in a lecture, I shall on the present