scorn to employ it? But it may be asked, how can the brain enlarge or decrease by the action of the mind? Can an invisible, immaterial principle enlarge or lessen the organ through which it operates? most certainly it can,--what but _use_ developes the muscular system--what but the amount of exertion makes the right arm of the gold beater nearly twice the size of his left? or why does active exertion give strength and tone to the limbs, whilst indolence renders them effeminate and small,--and if any one doubt the parallel, they cannot have examined and enquired for truth, on which alone enquiry can be based. Muscular power, considered abstractedly, is to the full as invisible and deep seated as the powers of the mind,--the mind must first direct the motions of animal power through the medium of the nerves, and the exertion of their power forms the muscles, or if the power be not exerted, the muscles, however fully developed previously, must quickly decrease; so it is with the brain, the index of the mind: and as no one can behold the brawny frame of the laborious artisan without being led to consider the exertion of muscular force as the cause of that powerful form, so no one ought to dispute the identical operation in another part of the human system, simply because they _are_ familiar with one and _will not_ be familiar with the other. Taking it for granted then, (and surely no one will deny rashly what countless facts have proved, and what is only proved the more as the number of facts increase) that the brain is the organ of the mind, we are led to the following principles. 1. The brain is the organ through which the mind operates. 2. In proportion to the developement of any part of the brain will be the power of that corresponding faculty, sentiment, or passion, because that faculty, sentiment, or passion, by its _anterior action_, has developed the brain. 3. The increase or decrease of mental passions, affections, or sentiments, is accompanied by a corresponding increase or decrease of the brain. 4. The brain like the muscle, is only the agent through which the immaterial spirit acts, for as muscular power resides not in a muscle, so neither does the mind dwell in the brain;--and as all connection between the muscle and life, or vital energy is destroyed by severing the connection of the nerve communicating power to that muscle, so might the mind and brain be severed, but for the beautiful design of Providence, in so carefully protecting the brain lest any mental organ be impaired, as well as by the formation of duplicates to those organs most exposed to injury; for as in common life, the accident that deprives man of a limb, does not render him incapable of his higher and loftier duties, so is it proportionably necessary that the organ through which those higher and nobler functions are performed should have been rendered most secure from harm.