For the insurance of this sense of touch, and feeling, and perception, it is essential that the impression at the end of a nerve shall be perfectly transmitted along its course to the brain, so that the brain shall be conscious, or sensible of this impression. For if a nerve be cut asunder, or a ligature be placed on any portion of it between the skin and the brain, the sensation instantly ceases. It is not essential, however, that the contact should take place at the moment of the perception; and the explanation of this involves one of the most curious phenomena of the body’s feeling; and, indeed, the metaphysical mystery of the nature of memory, which is too abstruse a point to be touched by us here. After amputation, the patient may still complain of pain, and heat, and cold, in the dissevered limb; he experiences the memory of a sensation; he feels, as it were, the ghost of his arm or leg. On the night succeeding the operation, the groaning patient has often cried out to me, with pain in the toe or finger of that limb; and when he is moved or shifts his position, he will attempt to hold his leg, or will beg his nurse to take care that she does not touch or run against it. Nay, I have frequently, on asking a patient how he felt, even after the lapse of many months from the operation, been answered, that he was well, but had not lost the pain in his leg; or that his leg or his arm were lying by his side, when perhaps the limb was undergoing the process of maceration in the dissecting-room, or the bones were bleached and dangling in the museum.
The pain, or common feeling of the limb, has stamped an image or eidōlon on the brain, which is not easily effaced; there remains an internal sensibility on this point of memory. If the subject be subsequently presented to the mind by a touch at the end of the stump, or even by a thought, the idea of the limb that had lain dormant, will be re-excited by that wondrous sympathy of brain and nerve, and the result will be a consciousness of having once possessed, or of having experienced a pain in this leg.
And, on this principle of the force of memory, we may explain many of our excited feelings: those which remain after we have been wafted in a boat, or rolled along in a carriage, or whirled aloft in a swing; the nervous impression in the brain is re-excited ere it was exhausted.
Now, an image may be stamped on the brain, in a tumult, without our cognizance or perception, and then revived in slumber;—we wake in wonder at having seen what we never saw or thought of before. Such is the dream of Lovel, in the “Antiquary;” and such the rationale of that tale of mystery, respecting the £6. in the Glasgow bank, which a dream seems certainly to have developed.
And it is evident that these impressions may recur the easier in slumber, because there is no fresh impression on the senses to produce confusion. But then all these images may be presented at one time; so that we may have either a chaos, or a correct concatenation,—an incident, which Hobbes and other early metaphysicians confess to be inexplicable to them.
In the words of Spurzheim, “Memory is the reproduction of a perception;” and Gall believed that “Remembrance is the faculty of recollecting that we have perceived impressions; and memory, the recollection of the impressions themselves.”
I read, that Esquirol has drawn a distinction between hallucination and illusion,—the first is from within, the second from without. The argument I have adduced of memory and impression,—the one at the beginning, the other at the end, of nerves,—will, I think, illustrate this perfectly. Hallucination, being internal, is of the past; illusion, external,—of the present.
Another metaphysician, Bayle, it is clear, was not ignorant of the basis of phrenology, or of this difference, when he alludes to “certain places on the brain, on which the image of an object, which has no real existence out of ourselves, might be excited.”
INTENSE IMPRESSION.—MEMORY.
“The dream’s here still: even when I wake, it is