40 SENSORI AL SECT. XI. 2. 3 . 



expofed to too great a degree of cold. But thofe, whofe ftimu- 

 li are external to the body, are named from the objects, which 

 are by nature conftituted to excite them ; thefe defires originate 

 from our paft experience of the pleafurable fenfations they oc- 

 cafion, as the fmell of a hyacinth, or the tafte of a pine apple. 



Whence it appears that our pleafures and pains are at lead 

 as various and as numerous as our irritations ; and that our de- 

 fires and averfions muft be as numerous as our pleafures and 

 pains. And that as fenfation is here ufed as a general term for 

 our numerous pleafures and pains, when they produce the con- 

 tractions of our fibres ; fo volition is the general name for our 

 defires and averfions, when they produce fibrous contractions. 

 Thus, when a motion of the central parts, or of the whole fenfo- 

 rium, terminates in the exertion of our mufcles, it is generally 

 called voluntary action ; when it terminates in the exertion of 

 our ideas, it is termed recolletion, reafoning, determining. 



3. As the fenfations of pleafure and pain are originally in- 

 troduced by the irritations of external objects : fo our defires 

 and averfions are originally introduced by thofe fenfations ; for 

 when the objects of our pleafures or pains are at a diltance, 

 and we cannot inftantaneoufly poffefs the one, nor avoid the oth- 

 er, then defire or averfion is produced, and a voluntary exertion 

 of our ideas or mufcles fucceeds. 



The pain of hunger excites you to look out for food, the tree 

 that (hades you prefents its odoriferous fruit before your eyes, 

 you approach, pluck, and eat. 



The various movements of walking to the tree, gathering the 

 fruit, and malticating it, are affociated motions introduced by 

 their connexion with fenfation ; but if from the uncommon 

 height of the tree, the fruit be inacceflible, and you are prevent- 

 ed from quickly pofleffing the intended pleafure, defire is produ- 

 ced. The confequence of this defire is, firft, a deliberation a* 

 bout the means to gain the object of pleafure in proceis of time, 

 as it cannot be produced immediately ; and, fecondly, the muf- 

 cular action necefiary for this purpofe. 



You voluntarily call up all your ideas of caufation, that are 

 related to the effect you defire, and voluntarily examine and 

 compare them, and at length determine whether to afcend the 

 tree, or to gather ftones from the neighbouring brook, is eafier 

 to praclife, or more promifing of fuccefs ; and, finaJly, you 

 gather the ftones, and repeatedly fling them to diflodge the fruit. 



Hence then we gain a criterion to diftinguifh voluntary acts 

 cr thoughts from thofe caufed by fenfation. As the former are 

 always employed about the means to acquire pleafurable objects, 

 r the means to avoid painful ones \ while the latter are em- 

 ployed 



