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    Andre-Marie Ampere. Autograph Letter Signed.
    "A. Ampere." Five pages in French, 7.75" x 12.25, Paris; February 9, 1806. In this long letter to an unnamed correspondent, Ampere expresses sorrow for his friend's situation and responds to his friend's question concerning a metaphysical subject concerning muscular motion [English translation].

    "When I received your letter two days ago, my dear friend, I was expecting to be very pleased, only to feel crushed at the news of the terrible situation that has befallen you. How right you are about the need to resign ourselves to pain in this life. How I would love to be with you to share your grief and console you if that were possible.

    You ask me for a metaphysical reflection but I will not give you that today, however I will task myself with writing a thorough letter on that topic soon that I will bring to Mr. Romain of Germany when I am allowed to leave; in fact, although I am feeling better I remain quite sick. I have not resumed my work at the school [unclear if he is a student or a teacher] and I am forbidden from going outdoors. I wanted to ask one of my friends who visits me each day to bring this letter to Mr. Romain but I decided it was a favor I could spare him and I will only ask him to drop it in the nearest mailbox.

    There is but one metaphysical point on which you and I essentially differ and it is this: you confuse the meaning of effort and the meaning of muscular sensation. For me they are two entirely different things. When I move my arm I bring the muscular sensation to the arm like a toothache does to the jaw, I feel the effort in my brain and I bring it in, like men who do not know what the brain even is inside their head, it is an interior impression and purely cerebral, or if you want to think about it, produced by the motion in the nervous fluid that is aroused by the hyper-physical ["hyper-organique" or "hyper-physiological"] rather than by the brachial nerve that constitutes the self. Whosoever has thought of placing their self, their willful being, into the member they are moving at any moment, and to which they are bringing back the muscular sensation; the impression produced in the brain by the sudden movement of our eternal soul, for us in our standby state, becomes so familiar that we hardly notice it when we aren't paying attention to it, but at the slightest return to the self one feels it as a strictly distinct impression, different from the muscular sensations that come from the organs through the nerves, an impression aroused by the internal willful force acting upon the brain; the muscular sensation that comes to the brain through the brachial nerve is, in this regard, in the same category as all other muscular sensations; like them, it is brought in without effort insofar as it comes through a nerve, and that it is transmitted by the nerve to the brain from another organ. This muscular sensation would be felt without a self by a child whose arm we would shake before his self-acted; in what way, then, is muscular sensation remarkable? It is remarkable in that when we then act voluntarily, we feel simultaneously the sudden impression of effortfulness that we produce in the brain as well as that very impression abstracted from effortfulness, and while these two impressions are exclusive to one another we also perceive the causal link between them, that is cause on the one hand (the impression of effortfulness) and effect on the other (the muscular sensation transmitted through the brachial nerve to the brain). From there comes our idea that one thing causes the other; causality is the perceived link between that which we term cause and that which we term effect, and a link can be perceived only between two things exclusive to one another.
    When the aim of effort is to increase a cerebral impulse, which is the case in what we call attention, it is no longer separate from its effect since these are two impressions on the same part of the brain, the one coming from the nerve and the second coming from the hyper-physical force.
    According to the general rule, these two impressions must come together as one, this is what happens to me constantly; I no longer perceive my self as distinct when I concentrate on any given notion, just as when I carry out any muscular effort; the more I concentrate my attention, the more I lose my self, this is something I have verified on numerous occasions, [the following portion of this paragraph is especially confusing] in the case of all other theories one must explain this but in the case of my theory it is an inevitable consequence of the universal law of distinguishing between impressions made in different parts of the brain, so much so that if it were not the case, the observations I have made on said numerous occasions would be very difficult to explain.
    Based on these points, you could not then ask me if when a man blocks my effort, I have the immediate perception of a force foreign to my own, since that would be asking me if apart from the muscular sensation that results from his blocking me, I also feel the sensation of his self in his brain, an impression only he can perceive; but, just as when I give myself muscular sensations, I feel, apart from that sensation and in my brain, an effort which I recognize as the cause of the sensations, and I feel nothing of the sort when another man, that by the way I neither see nor touch with my other hand, moves one of my arms; I naturally hypothesize an effort analogous but foreign to my own and to the muscular sensations this man produces on me, and simultaneously hypothesize a causal link between this hypothetical effort and the muscular sensations I experience.
    You understand from all this that I reject a priori Mr. Engel's theory [Johann Jakob Engel (1741-1802) was a German writer, theater director, and philosopher] without even having read it. I understand from what you have told me that he attributes cause to the muscular sensation transmitted through the nerves to the brain rather than that other perception, or aperception if you will, of the soul's instantaneous action upon the brain, and of the modification or motion that the soul produces there.
    If at first this is only perceived when movement is voluntary, that is because the child never acts on his brain simply to act on his brain but always in order to transmit an action to the part of his body he wishes to move; presently, we produce and feel this effort even at rest provided we are awake.

    Here are, my dear friend, some ideas I submit to you, although my reflection on these matters leaves me no ounce of doubt. Take special care of your health, seek distractions from your grief in metaphysics; nothing is more harmful than abandoning yourself to suffering, and I believe I feel from here all that which you suffer.

    I embrace you with all my spirit and will complete the commissions you have given me for our friends the metaphysicians as soon as I can go out.

    I await the letter you promised me with great impatience."

    André-Marie Ampère (1775-1836) was a French physicist and mathematician who was one of the founders of the science of classical electromagnetism, which he referred to as "electrodynamics." He is also the inventor of numerous applications. An autodidact, Ampère was a member of the French Academy of Sciences and professor at the École polytechnique and the Collège de France. The unit of measurement of electric current, the ampere, is named after him.

    A fascinating letter by Ampere on muscular sensation.

    Condition: The letter has a horizontal fold and is stapled together on the left hand side; otherwise very good.

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