Let me tell of a curious little episode of Dr. Darwin’s, which will aid me in my illustration. A young lady was playing on the piano a very elaborate piece of music. It was correctly and scientifically performed, although she was agitated during her task; and when it was over, the lady burst into tears. She had been watching all the time a favourite canary in the fluttering of death; and with this catastrophe her _mind_ was almost wholly occupied, but her _fingers_ did not err in their complicated and delicate motions, which they undoubtedly would have done, if the will or mind alone had directed them. In sanity of mind, and in mania, the most philosophical distinction is based on the _health_ or _disease_ of memory. The ecstacy of madness may not seem perhaps more irrational than an ecstatic vision, but the maniac will not re-word the matter; whereas the mere visionary will repeat the action of the trance as a dream. ASTR. But there is a sort of somnambulism the reverse of this. In the retreat to Corunna, many of the soldiers, although exhausted by a long march, and having actually fallen asleep, continued to move forwards, leaving their companions behind, who halted and laid down to repose. EV. This is the _continued association_ of that excitement which has produced muscular motion. The mind was exhausted and sleepy, the brain was inert; but we believe that the spinal marrow does, of itself, effect motion, while the will and consciousness sleep; and we may also _stand_ and sleep. These soldiers did not walk in their sleep, but slept in their walk. ASTR. I am informed, too, that Richard Turpin, in allusion to his famous flight to York, asserted that Black Bess appeared to gallop unconsciously. EV. It is true; and when we reflect on this gigantic feat, we may suppose that the mare gallopped the farther, because her _consciousness of fatigue was not awake_, and her muscular energy was thus concentrated. Paralyzed muscles will often quiver when the sound limb is quiet; the brain’s influence being, in this case too, inert, sensation is diminished; but _involuntary_ motion continues from a habit in the muscle, or the excitement of unexhausted irritability, as in _chorea_, spasm, &c. And in some cases of _post mortem_ galvanism, Dr. Dunbar, of Virginia, passed the _galvanic aura_ along the _ulnar_ nerve of an executed negro, and the fingers instantly quivered, and assumed the attitude and action of one playing on a flute or the strings of a violin. ASTR. It is possible, then, to move without our _willing_ to do so, or being conscious of our act. EV. There are believed to be, indeed it is almost a demonstration,—_four sets of nerves_, traced along the spinal marrow. Two to the brain, of _sensation_ and _volition_, by which the mind feels what the body touches, and transmits its will to the muscles; two others to the marrow, by which _it_ also is stimulated by outward touch, and by which _it_ excites the muscles to motion.