IN your issue of January 18, you refer (on p, 271) to an article by Dr. Wilks in the Medical Magazine (which I have not seen), in which the learned author points out that music is not to be regarded in its origin as a purely spiritual faculty, but that it admits of a physiological explanation. This discussion is in itself a most interesting one. Dr. Wallace, in his well-known discussion of the relations of music to the other faculties of man, has raised this very question, or one closely allied to it. Wallaschek, as quoted by Dr. Wilks and yourself, asserts that “rhythm, or keeping time, lies at the very foundation of the musical sense.” Rhythm again, he says, “can be referred to muscular contraction and relaxation,” the “muscular sense being the measure of time,” so that the muscular sense is intimately bound up with the idea of music. “Not in the different passions of the mind, but in muscular action, therefore, music appears to have had its origin.”