SECT.XXXtV. i. DISEASES OF VOLITION, 4 5 



3. Hence when any violent pain afflicts us, of 

 which we can neither avoid nor remove the caufe, 

 we foon learn to endeavour to alleviate it, by ex- 

 erting fome violent voluntaiy effort, as mentioned 

 above ; and are naturally induced to ufe thofe muf- 

 cles for this purpofe, which have been in the early 

 periods of our lives mod frequently or mod power- 

 fully exerted. 



Now the firft mufcles, which infants ufe moft 

 frequently, ate thofe oi: refpi ration ; and on this ac- 

 count we gain a habit of hoU iug our breath, at 

 the fame time that we ufe great efforts to exclude 

 it, for this purpofe of alleviaiing unavoidable pain; 

 or we prefs out our breath through a fmall aperture 

 of the larynx, and fcream violently, when the pain 

 is greater than is relievable by the former mode of 

 exertion. Thus children fcream to relieve any pain 

 either of body or mind, as from anger, or fear of 

 being beaten. 



Hence it is curious to obferve, that thofe animals, 

 who have more frequently exerted their mufcles of 

 refpiration violently, as in talking, barking, or 

 grunting, as children, dogs, hogs, fcream much 

 more, when they are in pain, than thofe other ani- 

 mals, who ufe little or no language in their com- 

 mon modes of life ; as horfes, iheep, and cows. 



The next moft frequent or mod powerful efforts, 

 which infants are firft tempted to produce, are thofe 

 with the mufcles in biting hard fubitances ; indeed 

 the exertion of thefe mufcles is very powerful in 

 common maftication, as appears from the pain. 

 we receive, if a bit of bone is unexpectedly 

 found amongft our fofter food ; and further ap- 

 pears from their a&ing to fo fo great mechanical 

 difadvantage, particularly when we bite with the 

 incilores, or canine teeth, which are firft formed, 

 and thence are firft ufed to violent exertion. 



Hence 



