326 DISEASES SECT. XXXIV. i. i, 



the mufcles, as in epileptic fits, may in the common fenfe of that 

 word be termed involuntary , becaufe no deliberation is interpo- 

 fed between the defire or averfion and the confequent aclion j 

 but in the fenfe of the word, as above defined, they belong to 

 the clafs of voluntary motions, as delivered in VoL I Clafs III. 

 If this ufe of the word be difcordant to the ear of the reader, 

 the term morbid voluntary motions, or motions in confequencc 

 of averfion, may be fubflituted in its (lead. 



If a perfon has a defire to be cured of the ague, and has at the 

 fame time an averfion (or contrary defire )to fwallowing an ounce 

 of Peruvian bark ; he balances defire againft defire, or averfion 

 againft averfion ; and thus he acquires the power of choofing, 

 which is the common acceptation of the word 'willing. But in 

 the cold fit of ague, after having difcovered that the al of 

 fhuddering, or exerting the fubcutaneous mufcles, relieves the 

 pain of cold ; he immediately exerts this aft of volition, and 

 ihudders, as foon as the pain and confequent averfion return, 

 without any deliberation intervening ; yet is this al, as well as 

 that of fwallowing an ounce of the bark, caufed by volition ; and 

 that even though he endeavours in vain to prevent it by a weak- 

 er contrary volition. This recals to our minds the (lory of the 

 hungry afs between two hay-flacks, where the two defires are 

 fuppofed fo exactly to counteract each other, that he goes to 

 neither of the flacks, but perifhes by want. Now as two equal 

 and oppofite defires are thus fuppofed to balance each other, 

 and prevent all adtion, it follows, that if one of thefe hay-flacks 

 was fuddenly removed, the afs would irrefiftibly be hurried to 

 the other, which in the common ufe of the word might be call- 

 ed an involuntary aft ; but which, in our acceptation of it, 

 would be clafTed amongft voluntary aftions, as above explained. 



Hence to deliberate is to compare oppofing defires or aver- 

 iions, and that which is the moft interefling at length prevails, 

 and produces aclion. Similar to this, where two pains oppofe 

 each other, the ftronger or more interefling one produces ac- 

 tion j as in pleurify the pain from fufFocation would produce 

 expanfion of the lungs, but the pain occafioned by extending 

 the inflamed membrane, which lines the cheft, oppofes this ex- 

 panfion, and one or the other alternately prevails. 



When any one moves his hand quickly near another performs 

 eyes, the eye-lids inflantly clofe ; this al in common language 

 is termed involuntary, as we have not time to deliberate or to 

 exert any contrary defire or averfion, but in this work it would 

 be termed a voluntary al, becaufe it is caufed by the faculty of 

 volition, and after a few trials the nictitation can be prevented 

 by a contrary or oppofing volition. 



The 



