CLASS III. i. i. OF VOLITION. 277 



to no, when they lie down again in their beds. Whence it 

 appears, that when a very quick pulfe accompanies convulfion 

 or infanity, it limply indicates the weakness of the patient ; that 

 is, that the expenditure of fenforial power is too great for the 

 fupply of it. But if the ftrength of the patient is not previoufly 

 exhaufted, the exertions of the mufcles are attended with tem- 

 porary increafe of circulation, the reciprocal fwellings and elon- 

 gations of their bellies pufh forwards the arterial blood, and 

 promote the abforption of the venous blood ; whence a tempo- 

 rary increafe of fecretion and of heat, and a ftronger pulle. 



A correfpondent acquaints me, that he finds difficulty in un- 

 derftanding how the convulfions of the limbs in epilepfy can be 

 induced by voluntary exertions. This I fufpect firft to have 

 arifen from the double meaning of the words " involuntary mo- 

 tions ;" which are fometimes ufed for thofe motions, which are 

 performed without the interference of volition, as the pulfations 

 of the heart and arteries ; and at other times for thofe actions, 

 which occur, where two counter volitions oppofe each other, 

 and the ftronger prevails ; as in endeavouring to fupprefs laugh- 

 ter, and to (top the mudderings when expofed to cold. Thus 

 when the poet writes, 



video meliora, proboque, 



Deteriora fequor. 



The ftronger volition actuates the fyftem, but not without the 

 counteraction of unavailing fmaller ones ; which conftitute de- 

 liberation. 



A fecond difficulty may have arifen from the confined ufe of 

 the words " to will," which in common difcourfe generally 

 mean to choofe after deliberation ; and hence our will or voli- 

 tion is fuppofed to be always in our own power. But the will 

 or voluntary power, acts always from motive, as explained in 

 Sea XXXIV. i. and in Clafs IV. i. 3. 2. and III. 2. i. 12, 

 which motive can frequently be examined previous to action, 

 and balanced ngainlt oppofitc motives, which is called delibera- 

 tion ; at other times the motive is fo powerful as immediately 

 to excite the fenforial power of volition into action, without a 

 previous balancing of oppofite motives, or counter volitions. 

 The former of thefe volitions is exercifed in the common pur- 

 pofes of life, and the latter in the exertions of epilepfy and in- 

 fanity. 



It is difficult to think without iuordr t which however all thofe 

 mud do, who difcover new truths by reafoning , and (lill more 

 difficult, when the words in common ufe deceive us by their 



twofold 



