INTRODUCTION. y 



would accompany an actual experience of the evil feared. 

 The destructive passions are shown in a general tension 

 of the muscular system, in gnashing of the teeth and 

 protrusion of the claws, in dilated eyes and nostrils, 

 in growls; and these are weaker forms of the actions 

 that accompany the killing of prey." Here we have, 

 as I believe, the true theory of a large number of expres- 

 sions; but the chief interest and difficulty of the subject 

 lies in following out the wonderfully complex results. I 

 infer that some one (but who he is I have not been able 

 to ascertain) formerly advanced a nearly similar view, 

 for Sir C. Bell says, 9 " It has been maintained that what 

 are called the external signs of passion, are only the con- 

 comitants of those voluntary movements which the struc- 

 ture renders necessary." Mr. Spencer has also pub- 

 lished 10 a valuable essay on the physiology of Laughter, 

 in which he insists on "the general law that feeling 

 passing a certain pitch, habitually vents itself in bodily 

 action; " and that " an overflow of nerve-force undirected 

 by any motive, will manifestly take first the most 

 habitual routes; and if these do not suffice, will next 

 overflow into the less habitual ones." This law I believe 

 to be of the highest importance in throwing light on our 

 subject. 11 



9 ' The Anatomy of Expression,' 3rd edit. p. 121. 



10 ' Essays, Scientific, Political, and Speculative,' Second 

 Series, 1863, p. 111. There is a discussion on Laughter in 

 the First Series of Essays, which discussion seems to me 

 of very inferior value. 



11 Since the publication of the essay just referred to, 

 Mr. Spencer has written another, on " Morals and Moral 

 Sentiments," in the ' Fortnightly Review,' April 1, 1871, p. 

 426. He has, also, now published his final conclusions in 

 vol. ii. of the second edit, of the ' Principles of Psychology,' 

 1872, p. 539. I may state, in order that I may not be ac- 

 cused of trespassing on Mr. Spencer's domain, that I an- 

 nounced in mv ' Descent of Man,' that I had then written 

 a part of the present volume: my first MS. notes on the 

 subject of expression bear the date of the year 1838. 



2 



