in what the mysterious principle of life consists? Various theories have been broached, with which, no doubt, a gentleman of your intelligence and extensive information is well acquainted;—and life has been successively stated to depend upon the heart, the brain, the circulation of the blood, and the respiration of the lungs. All, however, are fallacious; the heart has been wounded, and the brain has been removed, and yet the patient has lived, whilst the operations of respiration and circulation have been kept up for hours, in a body from which the vital spirit had departed. Weighing all these and divers other arguments in my mind, it has struck me, and indeed I may say, that after mature deliberation, I have confidently arrived at the conclusion, that both the faculties which we call life and soul depend entirely upon the nervous system. Do not all philosophers agree that we receive ideas merely through the medium of the senses? And can our senses be operated upon otherwise than through the influence of the nerves? Ergo, the nerves alone convey ideas and sensations to the mind—or rather, the nerves alone are the mind.
