It is only just and right, and not inconsistent with true human knowledge, if physical science should commence with the study of man. Still, if we would contemplate man from the side of nature, it seems the safer course to endeavor, first of all, to obtain a clear and leading idea of the whole of his constitution in this respect, rather than to lose ourselves in the contemplation of the special phenomena of a particular sphere. Now, with regard to the whole of man's organization, the organic body as the third constituent of human existence, I will merely remark that, just as the triple principle of body, soul, and spirit is repeated in the special and narrower spheres of the senses, the instincts, and the passions, and even in the different forms in which a disordered intellect usually manifests itself, so also it admits of a further application to the organic body in general. That most wonderful organization, the marvelous structure of bones and muscles, the outward organic frame, is, as it were, the body in a narrower sense, the pre-eminently material constituent of living bodies. The soul of man--here consequently the organic soul--is in the blood and in the five or six organs whose functions are first of all to elaborate the blood and afterward to provide for its circulation--or perhaps by maintaining a perpetual interchange of the breath and the external air, to keep the vital flame constantly burning on the hearth of life within. A third element--and, indeed, the principal one of the three, though only noticeable in its effects on the brain--exists within the higher senses and functions--in short, in the whole nervous tissue. But it lies not in the nervous filaments themselves: anatomy can not detect it, for it is not visible to the eye. On this account some have called it the æther of the nerves to indicate its incorporeal nature--incorporeal, _i.e._, relatively to, and in comparison with, the other two constituents of man--the blood-soul, and the external frame--as being the spirit of life in the organic body. Strictly and sharply enough does Holy Writ distinguish this spiritual body (as it calls it) of man from the body of the soul, or the organic blood-soul, considering the former, as it were, the seed of the resurrection, even because at the moment of death this ethereal body-of-light leaves its terrestrial veil to be in due time reunited to it after a more glorious fashion. And death itself is even nothing else than its total departure and painful emancipation from the organic body, on which the features, one might almost say, the physiognomy of corruption stamps itself, immediately that the immortal Psyche, the invisible seed of light and eternity, has put off the tabernacle of this body.