523

Richard Reece , M. D., had dedicated to me the first edition ofhis Medical Guide, and in April, 1810, he sent me the seventhedition of it, and requested me to read a few pages (from the 15thto the 19th) of the introduction to the first part, and to favourhim with my opinion of it. I sent him the subjoined letter, datedMay 12th, 1810: —

“ Sir,

“ After returning you my best thanks for the present of yourbook, which I have just received, I must observe that it is not mycustom to give an opinion of any book lest I should usurp theprovince of a reviewer. I have, however, read the pages withpleasure, which you have recommended to my perusal.

“ I am not wholly unacquainted with what has been written byvarious authors on the vibrations of ether, on electrical muscularmotions, on animal spirits, on nervous fluids, on irritability, asdistinguished from sensibility, and on other theories, which havebeen formed in different ages and countries, to explain animalphysiology; but I own that I have looked upon them all withthe suspicion of their being ingenious hypotheses rather thansolid truths experimentally established; and you must excuse meif I do not consider your electrical fire excited by and emanatedfrom the brain in any other light.

“ I allow the whole of your system to be ingenious, and thinkthat it may be of practical utility in the art of healing; but Idespair of ever seeing the question clearly decided, Whether thebrain is the efficient or the instrumental cause of sensation ?

“We can comprehend how light, entering the pupil of an eye,

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