Let us then, in this place, return to the sublime conjecture of Franklin, a man habitually conversant with the system of the external universe, and by no means propense to extravagant speculations, that "mind will one day become omnipotent over matter." The sense which he annexed to this expression, seems to have related to the improvements of human invention, in relation to machines and the compendium of labour. But, if the power of intellect can be established over all other matter, are we not inevitably led to ask, why not over the matter of our own bodies? If over matter at however great a distance, why not over matter which, ignorant as we may be of the tie that connects it with the thinking principle, we seem always to carry about with us, and which is our medium of communication with the external universe?
The different cases in which thought modifies the structure and members of the human body, are obvious to all. First, they are modified by our voluntary thoughts or design. We desire to stretch out our hand, and it is stretched out. We perform a thousand operations of the same species every day, and their familiarity annihilates the wonder. They are not in themselves less wonderful, than any of those modifications we are least accustomed to conceive. Secondly, mind modifies body involuntarily. To omit, for the present, what has been offered upon this subject by way of hypothesis and inference, there are many instances in which this fact presents itself in the most unequivocal manner. Has not a sudden piece of good news been frequently found to dissipate a corporal indisposition?
Is it not still more usual for mental impressions to produce indisposition, and even what is called a broken heart? And shall we believe that that which is so powerful in mischief, can be altogether impotent for happiness?
How common is the remark, that those accidents, which are to the indolent a source of disease, are forgotten and extirpated in the busy and active?