222 TRANSFORMATION AND EQUIVALENCE OF FORCES. 



pride there is a suppression of the screams and groans ex- 

 pressive of great pain (also indirect results of muscular con- 

 traction), we may still see in the clenching of the hands, 

 the knitting of the brows, and the setting of the teeth, that 

 the bodily actions developed are as great, though less ob- 

 trusive in their results. If we take emotions instead 

 of sensations, we find the correlation and equivalence 

 equally manifest. JsTot only are the modes of consciousness 

 directly produced in us by physical forces, re-transformable 

 into physical forces under the form of muscular motions 

 and the changes they initiate; but the like is true of those 

 modes of consciousness which are not directly produced in 

 us by the physical forces. Emotions of moderate intensity, 

 like sensations of moderate intensity, generate little beyond 

 excitement of the heart and vascular system, joined some- 

 times with increased action of glandular organs. But as 

 the emotions rise in strength, the muscles of the face, body, 

 and limbs, begin to move. Of examples may be mentioned 

 the frowns, dilated nostrils, and stampings of anger; the 

 contracted brows, and wrung hands, of grief; the smiles 

 and leaps of joy; and the frantic struggles of terror or de- 

 spair. Passing over certain apparent, but only apparent, 

 exceptions, we see that whatever be the kind of emotion, 

 there is a manifest relation between its amount, and the 

 amount of muscular action induced: alike from the erect 

 carriage and elastic step of exhilaration, up to the dancings 

 of immense delight, and from the fidgettiness of impatience 

 up to the almost convulsive movements accompanying great 

 mental agony. To these several orders of evidence 

 must be joined the further one, that between our feelings 

 and those voluntary motions into which they are trans- 

 formed, there comes the sensation of muscular tension, 

 standing in manifest correlation with both a correlation 

 that is distinctly quantitative: the sense of strain varying, 

 other things equal, directly as the quantity of momentum 

 generated. 



