An exhaustive analysis of the various classes of sensations, commonly grouped under the general heading of muscular sense, would involve a mass of technicalities not necessary to the present purpose. It is sufficient to bear in mind the limitations of this sense, and to notice what it tells us, and what it does not tell. Through the exercise of the muscular sense we are informed of the movements, positions, and conditions of the different parts of the body. Of specific muscular contractions very little information is conveyed. Thus, when the arm is bent at the elbow the muscular sensations of the movement are clear and definite; but, under normal conditions, these sensations do not inform us that the movement results from the contraction of the biceps muscle. Knowledge of the muscular structure of the body is not involved in muscular sense. The muscular sensations of bending the arm are felt in precisely the same way by the professor of anatomy and the ignorant child. Further, no amount of attention paid to muscular sensations will inform us exactly what muscles are contracted in any complex action. A single stroke in the game of tennis, returning a swift service for example, may involve some contraction of every muscle of the entire body. A skilful player may observe with the utmost care the muscular sensations accompanying this stroke; he would never be able to learn from these sensations whether the number of muscles in his forearm is ten or one hundred. For the same reason the sympathetic sensations of tone tell us nothing whatever of the muscular structure of the vocal organs. When listening to a throaty voice, we feel that the singer's throat is tightened, stiffened, or contracted. But no matter how keen and vivid this sensation may be, it leaves us in complete ignorance of the names and locations of the muscles wrongly contracted. This is true, however thoroughly we may know the anatomy of the vocal organs. Much of the prevailing confusion about the voice is due to a misunderstanding of this point. When, for example, the musical critic asserted that Mme. T---- sang certain tones with "pinched glottis," he fell into this error. His sympathetic sensations informed him of some unnecessary tightening of the singer's throat. From these sensations he seems to have inferred that the glottis-closing muscles were too strongly contracted. This assumption was not warranted by any information conveyed in the sympathetic sensations. It is not necessary now to determine to what extent the muscular sensations accompanying the listening to voices are purely imaginative, and to what extent they result from actual, though unconscious, contractions of the listener's throat muscles. The psychological process is the same in either case.