Selection from Apocalypse Explained ~ Emanuel Swedenborg
And I saw a beast coming up out of the sea having seven heads and ten horns, and upon his horns ten diadems, and upon his heads a name of blasphemy (Revelation 13:1)[T]he origins of all fibers are in the head, and from it they proceed to all the organs of sense and motion belonging to the face and the whole body; and there, too, are substances in infinite number that look like little spheres and are called by anatomists the cortical and cineritious substances; and from these go forth small fibers, the first of which are undiscernible; afterwards these are bundled together, and make up the medullary substance of the whole cerebrum, cerebellum, and medulla oblongata. From this medullary substance discernible fibers extend, and these when conjoined are called nerves. By these the cerebrum, the cerebellum, and the spinal marrow form the entire body and each and all things pertaining to it; and from this it comes that each and all things of the body are ruled by the brains.
From this it can be seen that the brains are the seat of the understanding and the will, which are called with one term, mind, and in consequence, of intelligence and wisdom, and that these are there in their first principles; also that the organs that are formed to receive sensations and to produce motions are derivations therefrom, precisely like streams from their fountains, or derivatives from their beginnings, or composite things from their substances; and these derivations are such that the brains are everywhere present, almost as the sun is present by its light and heat in each and all things of the earth.
From this it follows that the whole body, and each and all things of it, are forms that are under the observation, auspices, and obedience, of the mind, which is in the brain; thus these forms are so constructed after the mind's direction that any part in which the mind is not present, or to which it does not communicate its life, is no part of man's life.
From this it can be seen that when the mind is in its thought, which pertains to the understanding, and in its affection, which pertains to the will, it has an extension into every particular of the whole body, and there, by means of its forms, it spreads itself out as the thoughts and affections of the angels do into the societies of the universal heaven. The like is true here, since all things of the human body correspond to all things of heaven; consequently the form of the whole heaven before the Lord is the human form. (This is treated of at length in the Arcana Coelestia and in the work on Heaven and Hell.)
This has been said to make known why the "head" signifies wisdom and intelligence, as also in the contrary sense folly and insanity. For such as man is in his beginnings such is he in the whole, for the body with each and every part of it is a derivation, as has just been said. If, therefore, the mind is in the belief of falsity and in the love of evil, its entire body, that is, the entire man, is in a like state. This is also clearly evident when man becomes a spirit, whether good or evil; then his whole spiritual body, from head to foot, is wholly such as his mind is. If the mind is heavenly, the whole spirit, even as to its body, is heavenly. If the mind is infernal, the whole spirit, even as to its body, is infernal; and in consequence such a spirit appears in a direful form like a devil, while the former spirit appears in a beautiful form like an angel of heaven. ...
(Apocalypse Explained 775)