Robert Macnish, The Philosophy of Sleep ( 1830), 3rd edn. ( Glasgow, W. R. M'Phun: 1836), 187-8.
The case of the young American woman Mary Reynolds became one of the most famous instances of double or divided consciousness during the nineteenth century. Macnish's extended quotation of S. L. Mitchell's description of 'A double consciousness, or a duality of person in the same individual' ( Medical Repository, 3 ( Feb. 1816), 185-6) was widely cited in later discussions. These actively reinterpreted the case, arguing that Mary awoke to her 'second state' possessed of a mature consciousness, and emphasizing the dramatic difference in the personalities of the two Marys: the first quiet and sober, the second loquacious, witty, and and fond of practical jokes. See, for example, W. S. Plumer, "Mary Reynolds: A Case of Double Consciousness" in the American journal Harper's New Monthly Magazine, 20 ( 1860), 807-12.
A case was published in the Medical Repository, by Dr. Mitchell, who received the particulars of it from Major Ellicot, Professor of Mathematics in the United States Military Academy at West Point. The subject was a young lady, of a good constitution, excellent capacity, and well educated. 'Her memory was capacious and well stored with a copious stock of ideas. Unexpectedly, and without any forewarning, she fell into a profound sleep, which continued several hours beyond the ordinary term. On waking, she was discovered to have lost every trait of acquired knowledge. Her memory was tabula rasat1--all vestiges, both of words and things were obliterated and gone. It was found necessary for her to learn every thing again. She even acquired, by new efforts, the art of spelling, reading, writing, and calculating, and gradually became acquainted with the persons and objects around, like a being for the first time brought into____________________